Jaguar XK 5.0 No Compression in Engine / Needs New Heads?
Discussion
The engine management light on my XK 5.0 recently came on, along with the Restricted Performance warning. I took it in the main dealer and a new injector was diagnosed. This cured the problem. Then soon after the car lost all its water and I assumed this was because of the water pump and / or crossover pipe failing. I checked the oil cap and there was no mayonnaise.
However, I have now obtained all the previous receipts for the car and when the last owner took the car in to get the same misfire diagnosed, his main dealer diagnosed the following:
"Investigated report of customers concern of misfire. Carried out fault code read, cylinder block test, no compression in the engine, coolant pressure test, confirmed new heads required."
It seems very strange that the Jaguar main dealer I took the car to diagnosed and cured the car with an injector yet the other Jaguar main dealer thought the car needed new heads!
Greatly appreciate any advice on this - I guess I need to get the car compression tested myself but as I say, once the new injector was fitted the engine performed perfectly - surely if there was no compression in the engine a new injector would not cure this. What's strange though is that the car was driving 100% fine, surely if there was no compression in the engine, performance would be terrible.
However, I have now obtained all the previous receipts for the car and when the last owner took the car in to get the same misfire diagnosed, his main dealer diagnosed the following:
"Investigated report of customers concern of misfire. Carried out fault code read, cylinder block test, no compression in the engine, coolant pressure test, confirmed new heads required."
It seems very strange that the Jaguar main dealer I took the car to diagnosed and cured the car with an injector yet the other Jaguar main dealer thought the car needed new heads!
Greatly appreciate any advice on this - I guess I need to get the car compression tested myself but as I say, once the new injector was fitted the engine performed perfectly - surely if there was no compression in the engine a new injector would not cure this. What's strange though is that the car was driving 100% fine, surely if there was no compression in the engine, performance would be terrible.
It could have lost all compression on both banks if the timing chain had jumped or stretched, but as changing an injector fixed it I'd suggest their monkey didn't know how to use the compression tester.
Have you determined where the coolant went? Could you smell hot coolant? If you fill it back up does water pour out from a hose somewhere?
Have you determined where the coolant went? Could you smell hot coolant? If you fill it back up does water pour out from a hose somewhere?
It seems very strange that 2 franchise Jaguar main dealers diagnosed so differently - all I can think is maybe somehow the previous owner managed to bodge a temporary repair on the head gasket before I bought the car but I'd imagine this would be pretty difficult to say the least. The Jaguar dealer I went to said that one injector had seized whereas the previous owner's Jaguar main dealer made no mention of the injector at all! Surely even if it needs a new head, the first dealer should have diagnosed the injector too!
Am I right in thinking that a failed head gasket would not effect the injector and cause that to fail?
As far as I know the timing chain is fine - I did worry about this first when I saw the engine management light but as far as I can tell its fine as it doesn't rattle on the start up and once the injector was fixed, the car drove fine.
The coolant water just came out of the car and ran onto my drive. If I put my head near the tank I can smell coolant but not that bad. I filled it up and when the car is parked no water pours out. If I drive the car about a mile though the water goes down by about an inch. I gather that the water pump and / or crossover pipe as this seems a common fault with the 5.0 litre engine.
I'm really not sure what's best to do as I'm paranoid it needs new heads but I guess my best bet is to get it compression tested - hopefully a decent indie mechanic can tell me if it needs a head gaskets or not.
Thanks for your help
Am I right in thinking that a failed head gasket would not effect the injector and cause that to fail?
As far as I know the timing chain is fine - I did worry about this first when I saw the engine management light but as far as I can tell its fine as it doesn't rattle on the start up and once the injector was fixed, the car drove fine.
The coolant water just came out of the car and ran onto my drive. If I put my head near the tank I can smell coolant but not that bad. I filled it up and when the car is parked no water pours out. If I drive the car about a mile though the water goes down by about an inch. I gather that the water pump and / or crossover pipe as this seems a common fault with the 5.0 litre engine.
I'm really not sure what's best to do as I'm paranoid it needs new heads but I guess my best bet is to get it compression tested - hopefully a decent indie mechanic can tell me if it needs a head gaskets or not.
Thanks for your help
"Any dealer, or other garage, is only as good as the person working on your car.
No magic cure for no compression. Seems a poor diagnosis if the car was driven away and was ok."
It is a real mystery - I've never had a car with compression issues before so it's all a bit bizarre to me. As you say though, there is no magic cure for compression so if this was the problem, surely the car would be hugely lacking in power even after a new injector.
I'm a bit shocked at the moment but I just need to stand back and get it compression tested
No magic cure for no compression. Seems a poor diagnosis if the car was driven away and was ok."
It is a real mystery - I've never had a car with compression issues before so it's all a bit bizarre to me. As you say though, there is no magic cure for compression so if this was the problem, surely the car would be hugely lacking in power even after a new injector.
I'm a bit shocked at the moment but I just need to stand back and get it compression tested
Where in the country are you? You need a decent Jaguar indy/specialist, if you do find a Jaguar dealer who can do something more complicated that rob someone for a set of brake pads they don't need then the labour costs will be astronomical anyway.
If water ran out of the car then you have a leaking hose or pump. There is no bodge I can think of to take a V8 from compression issues on both banks that requires new heads to absolutely fine and running perfectly. Get your coolant leak fixed, if the car then drives fine then stop worrying.
If water ran out of the car then you have a leaking hose or pump. There is no bodge I can think of to take a V8 from compression issues on both banks that requires new heads to absolutely fine and running perfectly. Get your coolant leak fixed, if the car then drives fine then stop worrying.
I'm down in Dorset. I know what you mean about Jaguar dealers, they usually give me a list of health check advisories yet when the car is MoT'd elsewhere none of what they mention comes up!
Yes, exactly, water ran out of the car amazingly fast. Ironically, I was really enjoying a drive yesterday and when I pulled in, I couldn't believe that water was coming out of the car and the coolant tank was only about 10% full. (It was at the max when I got the car and has stayed there). There were no warning lights at all and the temp gauge stayed put in the middle.
I'm no mechanic to put it mildly, but in the past I've always assumed that contaminated water, lots of smoke and mayo on the oil cap point to a headgasket. My car has none of these symptoms.
Really appreciate you saying there's no bodge to cure a no cure a V8 with compression issues - I was honestly beginning to worry some mad temporary fix had been done to the car! I can definitely vouch for the fact that once the injector was replaced, the car performs fine. Even when not in sport mode, the performance is awesome.
Many thanks for your post - I am beginning to feel a bit better now. It was just a bit of a shock to the system when I saw the last owner's bill for the diagnosis of failed heads!! I'll get the compression test for peace of mind, then get the leak fixed and hope for the best! I have noticed that the car does get quite hot before but the temp gauge is always fine and I know that these V8s are designed to run hot. When the injector was replaced, the print out said the temp was about 97 degrees but I'm told this is normal.
Yes, exactly, water ran out of the car amazingly fast. Ironically, I was really enjoying a drive yesterday and when I pulled in, I couldn't believe that water was coming out of the car and the coolant tank was only about 10% full. (It was at the max when I got the car and has stayed there). There were no warning lights at all and the temp gauge stayed put in the middle.
I'm no mechanic to put it mildly, but in the past I've always assumed that contaminated water, lots of smoke and mayo on the oil cap point to a headgasket. My car has none of these symptoms.
Really appreciate you saying there's no bodge to cure a no cure a V8 with compression issues - I was honestly beginning to worry some mad temporary fix had been done to the car! I can definitely vouch for the fact that once the injector was replaced, the car performs fine. Even when not in sport mode, the performance is awesome.
Many thanks for your post - I am beginning to feel a bit better now. It was just a bit of a shock to the system when I saw the last owner's bill for the diagnosis of failed heads!! I'll get the compression test for peace of mind, then get the leak fixed and hope for the best! I have noticed that the car does get quite hot before but the temp gauge is always fine and I know that these V8s are designed to run hot. When the injector was replaced, the print out said the temp was about 97 degrees but I'm told this is normal.
hal3210 said:
It seems very strange that 2 franchise Jaguar main dealers diagnosed so differently
Well they both got one thing the same...a totally stupid and daft diagnosis.How the hell are so many garages and dealers so utterly incompetent to come out with such rubbish ?
Unless it has been lost in translation somewhere...for anyone to even say "no compression in engine" is just complete and utter BS of a statement to make.
Please find a garage that isnt full of total retards. I know it's hard, but it's what you need to do.
Of course the engine has compression but has it compression on all cylinders? Any local garage should be able to check that for you with a Halfords compression tester.
Buy a replacement header tank cap and see if that improves things. Fill the header tank to a midway mark, see what happens. I'd do this first.
If no improvement get the engine coolant system pressure tested and see what the result is. You won't need new heads, I'm pretty sure of that or a new timing chain.
Buy a replacement header tank cap and see if that improves things. Fill the header tank to a midway mark, see what happens. I'd do this first.
If no improvement get the engine coolant system pressure tested and see what the result is. You won't need new heads, I'm pretty sure of that or a new timing chain.
I'll definitely get the compression tested - I've had a good look at the cap and it seems fine. I'm sure the water isn't escaping from the cap. From what I've gleaned on the Jag forums, it seems like the water pump and crossover pipe is a weak point of this engine so I'd imagine this is what caused the coolant loss rather than a head gasket.
Thanks for saying you don't think I'll need new heads or a new timing chain - I am feeling better and better about it now. I know worrying doesn't help - I just have to take it stage by stage and let the mechanics do their thing. As you say, it shouldn't be rocket science for them to establish whether the heads need doing or not.
Thanks for saying you don't think I'll need new heads or a new timing chain - I am feeling better and better about it now. I know worrying doesn't help - I just have to take it stage by stage and let the mechanics do their thing. As you say, it shouldn't be rocket science for them to establish whether the heads need doing or not.
I have this engine in both my cars, a FFRR and an XKR.
The engine is genrally pretty bullet proof but the water pump on thm is a known weak spot, What you're describing 'could' just be you overfilling the coolant and the cooling system dumping excess when the engine gets up to temp but assuming you're not overfilling it could be as simple as the tank cap being a bit weak and allowing the coolant to escape when at full heat/pressure. Or it could be a leaking pipe, or the pump bearings starting to give up.
It's unlikley to be anything needing new cylinders heads
, gotta love bulls
t dealer garages.
See what the specialist says when he's had a look at it.
My FFRR started losing water on me a year or so back. I topped it up for a few hundred miles thinking I'd have time to investigate where the leak was coming from. Then the water pump completely shat itself on a decent run, the bearings just disintegrated, so be careful until you get it checked over.
My money is on tank cap or water pump. Neither expensive. Let us know how you get on.
The engine is genrally pretty bullet proof but the water pump on thm is a known weak spot, What you're describing 'could' just be you overfilling the coolant and the cooling system dumping excess when the engine gets up to temp but assuming you're not overfilling it could be as simple as the tank cap being a bit weak and allowing the coolant to escape when at full heat/pressure. Or it could be a leaking pipe, or the pump bearings starting to give up.
It's unlikley to be anything needing new cylinders heads
, gotta love bullst dealer garages. See what the specialist says when he's had a look at it.
My FFRR started losing water on me a year or so back. I topped it up for a few hundred miles thinking I'd have time to investigate where the leak was coming from. Then the water pump completely shat itself on a decent run, the bearings just disintegrated, so be careful until you get it checked over.
My money is on tank cap or water pump. Neither expensive. Let us know how you get on.
Hal,
you need to learn about compression testing. It refers to individual cylinders, and is done on all of them. "No compression" means nothing. "No compression on No.2" is useful. None on 2 and 3 indicates head gasket failure between the two bores if they are adjacent, and there are further refinements.
An engine with no compression at all is a dead engine! Could not be driven.
When you get your's done, you need to look for equal values across the block, within maybe 5%. Compression testers are not precision instruments, nor are they calibrated, so there is no absolute figure that should be achieved, just equality.
Good luck!
JOhn
you need to learn about compression testing. It refers to individual cylinders, and is done on all of them. "No compression" means nothing. "No compression on No.2" is useful. None on 2 and 3 indicates head gasket failure between the two bores if they are adjacent, and there are further refinements.
An engine with no compression at all is a dead engine! Could not be driven.
When you get your's done, you need to look for equal values across the block, within maybe 5%. Compression testers are not precision instruments, nor are they calibrated, so there is no absolute figure that should be achieved, just equality.
Good luck!
JOhn
Many thanks for your help Piers, it's really appreciated as I must have admit I've been constantly worrying about needing new heads since I discovered the receipt stating this from the previous owner!
I haven't touched the coolant since I've bought the car, it was always at 100% - even when I was a bit paranoid and thought the engine was getting pretty hot (which I'm sure is normal as we've previously discussed above) the water always stayed at 100%. It's hard to believe the main dealer thought the engine had no compression as once the injector was fixed, it drove fine.
It's really bizarre that about 90% of the water escaped after a pretty short drive the other day. I've had a good look at the cap and to be honest, I doubt the cap is causing the problem but as it's such a small item it's definitely worth trying a new one so I've just ordered one. When it comes, I'll top up the car with coolant and just leave it running in the drive and check if it still loses water.
As you say, the water pump definitely sounds the most likely cause - I understand that the crossover pipe can also be troublesome so if it is the water pump I'll probably get the crossover pipe changed at the same time. Hopefully the workshop that has been recommended to me will be able to diagnose it properly. Although I've always used Jaguar main dealers in the past, I'm beginning to think I'm best to go elsewhere for anything that is mechanical. At the end of the day, diagnosing a water pump shouldn't be anymore difficult on a Jaguar than a Ford.
I did wonder if it's something like a leaking pipe, simply because it happened so quickly. As I say my water level was 100% then shot down to 10% very quickly whereas with your RR was initially a more gradual water loss. If it is something like a leaking pipe it should be relatively easy for a decent mechanic to spot.
I'll let you know how I get on - the workshop is fully booked til next Friday though so in the meantime, apart from putting on the new cap, I'll try to stop worrying! Many thanks again
I haven't touched the coolant since I've bought the car, it was always at 100% - even when I was a bit paranoid and thought the engine was getting pretty hot (which I'm sure is normal as we've previously discussed above) the water always stayed at 100%. It's hard to believe the main dealer thought the engine had no compression as once the injector was fixed, it drove fine.
It's really bizarre that about 90% of the water escaped after a pretty short drive the other day. I've had a good look at the cap and to be honest, I doubt the cap is causing the problem but as it's such a small item it's definitely worth trying a new one so I've just ordered one. When it comes, I'll top up the car with coolant and just leave it running in the drive and check if it still loses water.
As you say, the water pump definitely sounds the most likely cause - I understand that the crossover pipe can also be troublesome so if it is the water pump I'll probably get the crossover pipe changed at the same time. Hopefully the workshop that has been recommended to me will be able to diagnose it properly. Although I've always used Jaguar main dealers in the past, I'm beginning to think I'm best to go elsewhere for anything that is mechanical. At the end of the day, diagnosing a water pump shouldn't be anymore difficult on a Jaguar than a Ford.
I did wonder if it's something like a leaking pipe, simply because it happened so quickly. As I say my water level was 100% then shot down to 10% very quickly whereas with your RR was initially a more gradual water loss. If it is something like a leaking pipe it should be relatively easy for a decent mechanic to spot.
I'll let you know how I get on - the workshop is fully booked til next Friday though so in the meantime, apart from putting on the new cap, I'll try to stop worrying! Many thanks again
Many thanks for the message John. I haven't had any compression issues before so it's not really something I've been aware of. As I say, the main dealer I took the car to diagnosed the misfire as needing a new injector and this cured the misfire completely. It's very strange one dealer said it was no compression and needed new heads whereas the other dealer said the car just needed an injector.
I'll definitely get the car compression tested to check there are no issues with compression but I'd imagine if there was a compression issue in any of the cylinders it would adversely effect the performance and this has not been an issue since the injector was fixed.
I'll definitely get the car compression tested to check there are no issues with compression but I'd imagine if there was a compression issue in any of the cylinders it would adversely effect the performance and this has not been an issue since the injector was fixed.
Somebody familiar with diagnosing compression problems would be able to identify any major problem just by listening to the engine cranking over. There are commonly available tools that do the same check based on the voltage variation as the engine resistance changes instead of relying on a person's judgment. These are non-invasive tests that only take a few seconds and would routinely be done before doing a fully compression measurement..
green,
Thank you! I didn't know that was possible. But is it useful?
This video demonstrates the test: https://www.youtube.com/watch?v=WKdZsWU2ZmI
But the operator says that the car being tested has a faulty head gasket, and then has to remove a spark plug to demonstrate the appearance onscreen of a cylinder with low compression! There's nothing to see to show the faulty gasket until he does so!
Also he says, there's no way onscreen to tell which cylinder is faulty! Obvious, done the traditional way.
So I'm afraid although I am grateful to be educated, I won't bother testing this way.
John
Thank you! I didn't know that was possible. But is it useful?
This video demonstrates the test: https://www.youtube.com/watch?v=WKdZsWU2ZmI
But the operator says that the car being tested has a faulty head gasket, and then has to remove a spark plug to demonstrate the appearance onscreen of a cylinder with low compression! There's nothing to see to show the faulty gasket until he does so!
Also he says, there's no way onscreen to tell which cylinder is faulty! Obvious, done the traditional way.
So I'm afraid although I am grateful to be educated, I won't bother testing this way.
John
tapkaJohnD said:
green,
Thank you! I didn't know that was possible. But is it useful?
This video demonstrates the test: https://www.youtube.com/watch?v=WKdZsWU2ZmI
But the operator says that the car being tested has a faulty head gasket, and then has to remove a spark plug to demonstrate the appearance onscreen of a cylinder with low compression! There's nothing to see to show the faulty gasket until he does so!
Also he says, there's no way onscreen to tell which cylinder is faulty! Obvious, done the traditional way.
So I'm afraid although I am grateful to be educated, I won't bother testing this way.
John
Given the reasons why you are considering compression testing (a red herring in my opinion), then I wouldn't entertain any test other than the conventional test and possibly then a leak down test.Thank you! I didn't know that was possible. But is it useful?
This video demonstrates the test: https://www.youtube.com/watch?v=WKdZsWU2ZmI
But the operator says that the car being tested has a faulty head gasket, and then has to remove a spark plug to demonstrate the appearance onscreen of a cylinder with low compression! There's nothing to see to show the faulty gasket until he does so!
Also he says, there's no way onscreen to tell which cylinder is faulty! Obvious, done the traditional way.
So I'm afraid although I am grateful to be educated, I won't bother testing this way.
John
But if the engine is running well, it's not a compression/new heads issue. To start and run any engine needs, fuel, compression, ignition and timing. Full loss of compression needing new heads wouldn't start, let alone run, or run well. If it was on 1 or 2 cylinders you would be getting a similar effect to a misfire.
Many thanks for the replies.
Coilspring, it's great to hear you consider the compression testing a red herring - I'm keeping everything crossed that the compression and heads are fine.
The engine was definitely running well after the new injector was fitted. I had a misfire when I first got the car but the seized injector was replaced and this cured the misfire. The car was still running fine when most of the water came out.
My simple logic is that if the car had no compression and needed new heads due to the misfire, fitting a new injector wouldn't have cured it.
As I say though, I've no experience of this before so am a bit baffled by it all to be honest.
I'm just wondering what my best approach with the workshop looking at the car should be? I've told them that I experienced rapid water loss and suspect the water pump/crossover pipe as these are common faults with the 5.0 engine but I haven't yet mentioned my fears that it could need new heads due to lack of compression. Shall I ask the workshop to test the compression before anything else? It just might sound a bit paranoid mentioning heads and compression as if I didn't see the receipt from the previous owner about this I would have never suspected it.
Coilspring, it's great to hear you consider the compression testing a red herring - I'm keeping everything crossed that the compression and heads are fine.
The engine was definitely running well after the new injector was fitted. I had a misfire when I first got the car but the seized injector was replaced and this cured the misfire. The car was still running fine when most of the water came out.
My simple logic is that if the car had no compression and needed new heads due to the misfire, fitting a new injector wouldn't have cured it.
As I say though, I've no experience of this before so am a bit baffled by it all to be honest.
I'm just wondering what my best approach with the workshop looking at the car should be? I've told them that I experienced rapid water loss and suspect the water pump/crossover pipe as these are common faults with the 5.0 engine but I haven't yet mentioned my fears that it could need new heads due to lack of compression. Shall I ask the workshop to test the compression before anything else? It just might sound a bit paranoid mentioning heads and compression as if I didn't see the receipt from the previous owner about this I would have never suspected it.
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