X308 hunting at tick over
Discussion
Hi folks,
Away on a trip down to Perthshire at the moment and have done well over 300 trouble free miles, when the Daimler Super V8 started hunting at tick over as if one pot was down. No warning lights or messages, no restricted performance and no lack of performance. No change in fuel consumption, just this tick over problem. I'll not be back home in Orkney until next week to investigate properly but I have plugged in the code reader and no stored or pending codes.
Same engine as XJR or XKR, anyone any ideas or had similar?
Ian
Away on a trip down to Perthshire at the moment and have done well over 300 trouble free miles, when the Daimler Super V8 started hunting at tick over as if one pot was down. No warning lights or messages, no restricted performance and no lack of performance. No change in fuel consumption, just this tick over problem. I'll not be back home in Orkney until next week to investigate properly but I have plugged in the code reader and no stored or pending codes.
Same engine as XJR or XKR, anyone any ideas or had similar?
Ian
Many thanks for tha JS,
We're at the Scottish Jaguar show today, often with the bonnet up, so I'll give it the once over. There will be many tyre kicking 'experts' present, suggesting rear wheel bearings and total gearbox box failure whilst sucking air through teeth😏
I had come down on the part throttle breather tube as a possible culprit as it runs fine off tick over. Will report back if I find anything,
Thanks again,
Ian
We're at the Scottish Jaguar show today, often with the bonnet up, so I'll give it the once over. There will be many tyre kicking 'experts' present, suggesting rear wheel bearings and total gearbox box failure whilst sucking air through teeth😏
I had come down on the part throttle breather tube as a possible culprit as it runs fine off tick over. Will report back if I find anything,
Thanks again,
Ian
Pop the part throttle breather off the cam cover. There's a calibrated 2.5mm bleed hole at the bottom of the fitting on the cam cover. Very gently clean out with a 2.5mm drill bit by hand - you do take one with you everywhere you go, right? 
My money is on a leak one of the several vacuum pipes connected to the throttle body but you'll never know until you've actually checked and rule every potential cause out with problems like this. Idle and engine overrun conditions pull the highest manifold vacuum and that's when small or intermittent induction leaks often manifest whilst under load or wider throttle openings the manifold vacuum is much lower and the leak stops and everything is OK.
My money is on a leak one of the several vacuum pipes connected to the throttle body but you'll never know until you've actually checked and rule every potential cause out with problems like this. Idle and engine overrun conditions pull the highest manifold vacuum and that's when small or intermittent induction leaks often manifest whilst under load or wider throttle openings the manifold vacuum is much lower and the leak stops and everything is OK.
Hi JS and anyone else interested.
Got back home to Orkney with no problems other than lumpy tick over but not really an issue with the fairly light traffic on the way to Scrabster for the Ferry.
Let it cool overnight and gave me a chance to think clearly. Bonnet up to check round as many vac pipes as you can actually see (and there are some!). Carefully squirted Easy Start around some of the bends and junctions with no change in revs. Just inquisitive, I sprayed some around the supercharger elbow and hey presto! Revs rose each time I was near the rubber seal plates. Without draining the coolant and with a bit of fiddling the elbow unit (the bit with the V8 logo on) can be released from the intake horns and up off the supercharger. This revealed very crusty rubber sleeves and a suspect gasket on the top of the charger. There is a modified kit available with everything needed to (hopefully) cure the problem.
I noticed at one point when pressing on (ahem!) that the brakes needed a bit more effort than normal, so the available vacuum was certainly compromised.
I'll post back when the bits arrive if the fault is completely gone.
Ian
Got back home to Orkney with no problems other than lumpy tick over but not really an issue with the fairly light traffic on the way to Scrabster for the Ferry.
Let it cool overnight and gave me a chance to think clearly. Bonnet up to check round as many vac pipes as you can actually see (and there are some!). Carefully squirted Easy Start around some of the bends and junctions with no change in revs. Just inquisitive, I sprayed some around the supercharger elbow and hey presto! Revs rose each time I was near the rubber seal plates. Without draining the coolant and with a bit of fiddling the elbow unit (the bit with the V8 logo on) can be released from the intake horns and up off the supercharger. This revealed very crusty rubber sleeves and a suspect gasket on the top of the charger. There is a modified kit available with everything needed to (hopefully) cure the problem.
I noticed at one point when pressing on (ahem!) that the brakes needed a bit more effort than normal, so the available vacuum was certainly compromised.
I'll post back when the bits arrive if the fault is completely gone.
Ian
Partial success!
As it was such an easy job to remove the necessary bits, I decided to inspect the seals a bit more closely this morning. There was evidence that one seal had been partially sucked into the elbow as there was a small split in the annular rib. I superglued this and then smeared all of the mating faces with blue Hylomar and reassembled. On startup everything was back to normal and ran like a bird for about 20 minutes up and down the rev range (upto the 3000rpm static limit on supercharged engines)
I'm not going to leave it like this and have ordered the modified kit from British Parts as I would not think my superglue 'bodge up' would be reliable over time. We are going over to Austria with it next year (if they'll let us in!) and you can bet your boots it would play up just as we close the front door of the house for the trip!
At least I know where the leak was from,
Ian
As it was such an easy job to remove the necessary bits, I decided to inspect the seals a bit more closely this morning. There was evidence that one seal had been partially sucked into the elbow as there was a small split in the annular rib. I superglued this and then smeared all of the mating faces with blue Hylomar and reassembled. On startup everything was back to normal and ran like a bird for about 20 minutes up and down the rev range (upto the 3000rpm static limit on supercharged engines)
I'm not going to leave it like this and have ordered the modified kit from British Parts as I would not think my superglue 'bodge up' would be reliable over time. We are going over to Austria with it next year (if they'll let us in!) and you can bet your boots it would play up just as we close the front door of the house for the trip!
At least I know where the leak was from,
Ian
Edited by Orcadian on Friday 1st July 10:46
Edited by Orcadian on Friday 1st July 10:47
Well, I'll go to foot of our stairs!
What a coincidence - the latest issue of Jaguar Enthusiasts magazine was amongst the pile of post when we got back. I have only just opened it to find an article on the very same problem with the supercharger elbow seals as mine, although on an XKR. He even sourced his parts from the same place.
I'm off to buy a lottery ticket!
Ian
What a coincidence - the latest issue of Jaguar Enthusiasts magazine was amongst the pile of post when we got back. I have only just opened it to find an article on the very same problem with the supercharger elbow seals as mine, although on an XKR. He even sourced his parts from the same place.
I'm off to buy a lottery ticket!
Ian
Update on the hunting.
Parts arrived this morning as promised. Pulled apart again - longest job was cleaning the Hylomar off that I had put on!
The kit is very comprehensive with the modified clamp plates, new tubular seals, new gasket which goes between the elbow and the supercharger and even the four special bolts and seals to hold the elbow to the charger.
I changed the original flanged bolts, which bind on the clamp plates making fitting more of a challenge than it need be, for some new stainless Allen cap screws lubed with duralac barrier grease.
About an hour in total and it fired up and purred away as normal. Out for a test run and it's even better than before and the brakes are back to normal too - it's amazing how you just don't notice these things creeping up on you. It would appear that some of my 370 horses have been languishing somewhere in the back of the stable for a while!
Very satisfying job
Ian
Parts arrived this morning as promised. Pulled apart again - longest job was cleaning the Hylomar off that I had put on!
The kit is very comprehensive with the modified clamp plates, new tubular seals, new gasket which goes between the elbow and the supercharger and even the four special bolts and seals to hold the elbow to the charger.
I changed the original flanged bolts, which bind on the clamp plates making fitting more of a challenge than it need be, for some new stainless Allen cap screws lubed with duralac barrier grease.
About an hour in total and it fired up and purred away as normal. Out for a test run and it's even better than before and the brakes are back to normal too - it's amazing how you just don't notice these things creeping up on you. It would appear that some of my 370 horses have been languishing somewhere in the back of the stable for a while!
Very satisfying job
Ian
Mines done 68k but these seals I took out had the modified lip but not the modified clamp plates, so it's had the issue before. Apparently the Jag Service Bulletin said no warranty action to be taken unless customer complained - bunch of penny pinching bar stewards!
It's not a big job to do but is there any way to find out if yours have been done?
Jaguar knew of the problem early days and even gave vin ranges on XKR and XJR but no Daimler SV8 even though they are the same.
As I said in an earlier post we will be having a long trip next year and I am of the mind that any prevention is better than a lift on a transporter so I will be replacing a few of these vulnerable bits, like the coolant pipes under the charger and might get rid of some of those piss poor plastic pipes around the very hot engine bay and replace with stainless if I can make some fittings. We have breakdown recovery but would have to hang my head in shame if I had to come home on the back of a truck from Austria - but think of the fuel we would save!!
Ian
It's not a big job to do but is there any way to find out if yours have been done?
Jaguar knew of the problem early days and even gave vin ranges on XKR and XJR but no Daimler SV8 even though they are the same.
As I said in an earlier post we will be having a long trip next year and I am of the mind that any prevention is better than a lift on a transporter so I will be replacing a few of these vulnerable bits, like the coolant pipes under the charger and might get rid of some of those piss poor plastic pipes around the very hot engine bay and replace with stainless if I can make some fittings. We have breakdown recovery but would have to hang my head in shame if I had to come home on the back of a truck from Austria - but think of the fuel we would save!!
Ian
The kit was just north of 200 quid delivered to Orkney including vat.
Not sure if it would be worth it if you don't have a problem, just for the sake of it. Try a squirt of easy start over the top of the joints and see if it does what mine did (speed up)
It's a doddle of a job to do, so I suppose you could check to see if yours has the modified clamp plates already.
We're away again at the moment in ours to a Jag show on Sunday at Drum Castle, Aberdeenshire and it's going like a dream, with all horses alive and kicking - I love it!!
Ian
Not sure if it would be worth it if you don't have a problem, just for the sake of it. Try a squirt of easy start over the top of the joints and see if it does what mine did (speed up)
It's a doddle of a job to do, so I suppose you could check to see if yours has the modified clamp plates already.
We're away again at the moment in ours to a Jag show on Sunday at Drum Castle, Aberdeenshire and it's going like a dream, with all horses alive and kicking - I love it!!
Ian
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