Discussion
Please don't shoot me but the search facility is down and I have a quick question regarding the coolant pressure caps on an S1 (although I know they're all the same).
My pressure cap is on the expansion/overflow tank and non-pressure is on the swirl pot. The car is running a few degrees hotter than I'd like so I figured I'd swap them around to the way the Bible states.
I checked, it's a 15lb pressure cap and I started the car up.
As it approached operating temp i could see water escaping from the swirl pot, but not going to the expansion tank, it was just leaking.
I could see that the pressure cap had "lifted" and was not sealing properly.
When I inspect the pressure cap I find it has no rubber seal at the top (above the pressure valve) - should it?
I put it all back to how it was before and adjusted the Kenlowe to have the fan come on sooner but it still feels like it's working hard to maintain an acceptable temperature.
The temp gauge seems to be almost always showing the needle on the white line when up to temperature, that's about 5 degrees hotter than I'd like.
Also the fan has to come on at motorway speeds which I hadn't expected, I checked the air intakes and they're all clear so I think I'll go for a "cooler" thermostat next (an 82) to see if that helps.
So the question really is - should the pressure cap have a rubber "gasket" where it mates to the top of the swirlpot?
My pressure cap is on the expansion/overflow tank and non-pressure is on the swirl pot. The car is running a few degrees hotter than I'd like so I figured I'd swap them around to the way the Bible states.
I checked, it's a 15lb pressure cap and I started the car up.
As it approached operating temp i could see water escaping from the swirl pot, but not going to the expansion tank, it was just leaking.
I could see that the pressure cap had "lifted" and was not sealing properly.
When I inspect the pressure cap I find it has no rubber seal at the top (above the pressure valve) - should it?
I put it all back to how it was before and adjusted the Kenlowe to have the fan come on sooner but it still feels like it's working hard to maintain an acceptable temperature.
The temp gauge seems to be almost always showing the needle on the white line when up to temperature, that's about 5 degrees hotter than I'd like.
Also the fan has to come on at motorway speeds which I hadn't expected, I checked the air intakes and they're all clear so I think I'll go for a "cooler" thermostat next (an 82) to see if that helps.
So the question really is - should the pressure cap have a rubber "gasket" where it mates to the top of the swirlpot?
Jules
Yes the cap should have a seal. Unfortunately it seems really difficult to buy a cap these days that does have one. I wanted to do just this before I took the car to Spa a month back, my seal looked a bit knackered and I thought it a good idea to fit a new cap and seal. My local trusty motor factors, who have pulled off the impossible on many occasions, were unable to find the correct cap with a seal. I ended up making one out of a motorcycle inner tube which worked perfectly.
Oh and by the way, the Bible says in a number of places the pressure cap should be on the swirl pot. I have seen a TVR service bulletin that backs this up also, so that is how I have mine and have had no issues.
Yes the cap should have a seal. Unfortunately it seems really difficult to buy a cap these days that does have one. I wanted to do just this before I took the car to Spa a month back, my seal looked a bit knackered and I thought it a good idea to fit a new cap and seal. My local trusty motor factors, who have pulled off the impossible on many occasions, were unable to find the correct cap with a seal. I ended up making one out of a motorcycle inner tube which worked perfectly.
Oh and by the way, the Bible says in a number of places the pressure cap should be on the swirl pot. I have seen a TVR service bulletin that backs this up also, so that is how I have mine and have had no issues.
Rad was replaced last year, I have flushed the system and replaced the coolant, even to the extent that I have diluted the anti-freeze to try to get a better temperature.
The thermostat is the next logical step I guess, shame it's in such a PITA place... Just need to get a termostat, seal & gasket then. What temperature thermostat are most people running?
The thermostat is the next logical step I guess, shame it's in such a PITA place... Just need to get a termostat, seal & gasket then. What temperature thermostat are most people running?
I had a water leak from the swirlpot and recently fitted a First line FRC069 Pressure Cap as recommended by someone on this forum (I'm sorry I can't remember who), cost £3-40 plus a couple of quid postage. It is 13 PSI and has a thin rubber seal between the cap and the top edge of the swirl pot. It is working fine.
One point I founds on mine was that the brass neck on the swirl pot is extremely soft & fragile and had tiny dents and uneven areas which stopped the cap seating properly even with the rubber seal (the seal is quite thin and doesn't have much give). It took a lot of trial and error to get the neck flat enough to seat the seal and stop it leaking. I will leave it to wiser and more knowledgeable people to advise on your other cooling issues.
One point I founds on mine was that the brass neck on the swirl pot is extremely soft & fragile and had tiny dents and uneven areas which stopped the cap seating properly even with the rubber seal (the seal is quite thin and doesn't have much give). It took a lot of trial and error to get the neck flat enough to seat the seal and stop it leaking. I will leave it to wiser and more knowledgeable people to advise on your other cooling issues.
Thanks All - There are a couple of things I need to check, as the car "just about" manages to maintain a reasonable temperature (allbeit with the fan working harder than I'd like) I don't think it's anything TOO major (but clearly it does need doing).
I need to see another S to see what the mesh should look like in the bonnet/bumper as mine seems to have quite small holes in and would be quite restrictive at a guess.
I also need to change the thermostat to rule that out, i'll track one down in the next day or two.
It looks as though changing the thermostat would be more easily accomplished from underneath the car (is that correct) in which case I may need to chuck it into a garage to get them to do it :-( as I don't have the facilities to get under it.
The next (minor) issue will be to get the correct thermostat housing gasket as I understand there are 2 varients for the 2.8 (LOL)
I'll make a thin rubber gasket for the pressure cap up and see if that does anything - AFTER I change the thermostat.
One other question - at the top of the swirlpot there is a second connection - not the one going to the overflow/expeansion tank. Mine has a length of hose attached and then "blanked", I am assuming this would normally be the bypass hose (correct?) in which case I need to check the thermostat housing to see where the bypass hose from there is going now...
You gotta love buying pre-owned cars, they're never quite how you expect them to be from looking in the book.
My issue is Possibly (in my order of suspicion):
1 Thermostat
2 Lack of airflow (restrictive grill mesh)
3 Some "weirdness" in the plumbing by a previous owner
4 Water pump
5 Head Gasket
I only put 5 in as it's always a possibility but the car's running great and isn't lumpy, there's no "smoke", it doesn't use/lose coolant, the oil is clean, the water is clean...
I think i'll get in there tonight with a torch and trace the bypass hose, and also check what the thermostat housing looks like so I can order the right gasket and thermostat (88 degree).
I need to see another S to see what the mesh should look like in the bonnet/bumper as mine seems to have quite small holes in and would be quite restrictive at a guess.
I also need to change the thermostat to rule that out, i'll track one down in the next day or two.
It looks as though changing the thermostat would be more easily accomplished from underneath the car (is that correct) in which case I may need to chuck it into a garage to get them to do it :-( as I don't have the facilities to get under it.
The next (minor) issue will be to get the correct thermostat housing gasket as I understand there are 2 varients for the 2.8 (LOL)
I'll make a thin rubber gasket for the pressure cap up and see if that does anything - AFTER I change the thermostat.
One other question - at the top of the swirlpot there is a second connection - not the one going to the overflow/expeansion tank. Mine has a length of hose attached and then "blanked", I am assuming this would normally be the bypass hose (correct?) in which case I need to check the thermostat housing to see where the bypass hose from there is going now...
You gotta love buying pre-owned cars, they're never quite how you expect them to be from looking in the book.
My issue is Possibly (in my order of suspicion):
1 Thermostat
2 Lack of airflow (restrictive grill mesh)
3 Some "weirdness" in the plumbing by a previous owner
4 Water pump
5 Head Gasket
I only put 5 in as it's always a possibility but the car's running great and isn't lumpy, there's no "smoke", it doesn't use/lose coolant, the oil is clean, the water is clean...
I think i'll get in there tonight with a torch and trace the bypass hose, and also check what the thermostat housing looks like so I can order the right gasket and thermostat (88 degree).
This is getting more interesting, the bypass hose is usually the cause of over cooling on the motorway, if yours is blanked off then the problem tends to point towards the thermostat. I think the normal rating is 88 degrees but you used to be able to get 95 degree ones. The grill mesh size is also important and could be a factor if it’s too small.
Out of interest my bypass hose is now routed to the bottom hose and the swirl pot connection blanked off as I was getting serious over cooling. The engine now heats up quickly and runs with the gauge between the middle and a couple of mm south of the white line. The fan comes on occasionally in crawling traffic. Mines a 2.9 S3.
Rob.
Out of interest my bypass hose is now routed to the bottom hose and the swirl pot connection blanked off as I was getting serious over cooling. The engine now heats up quickly and runs with the gauge between the middle and a couple of mm south of the white line. The fan comes on occasionally in crawling traffic. Mines a 2.9 S3.
Rob.
Julesprivate said:
2 Lack of airflow (restrictive grill mesh)
4 Water pump
5 Head Gasket
2. Does it look original, worked ok for last 20+ years ?4 Water pump
5 Head Gasket
4. Never known a water pump "wear out" (unless its a cheap copy item with a plastic impellor which could have broken/split etc.) Usually just seal/bearing failure, evident by noise/leaking.
5. As you say most unlikely, in my days of working on Ford V engines (mainly the earlier Essex versions but same principle) inlet manifold gasket failure was far more common than head gaskets, the waterways go through the manifold.
Mine, 2.9 S3 has always run smack on the white line ( 90 degrees?) come rain or shine
Good luck with getting it sorted.
Thanks
Only slight confusing thing there was "smack on the white line - 90 degrees" as mine has a 90 on the gauge then above that it has the white line.
I've set the Kenlowe up to come on as the needle is obscuring the top of the 90 and it does that, dropping it back to 90 just nicely, so I assumed that was somewhere in the 95-100 range to trigger the fan.
The fact that it needs to do it on the motorway too is the primary concern.
Hopefully I'll get a chance to sort this in the next week or two, but the car's still perfectly usable as it is so it's not massively problematic.
Thanks for the help...
I do need to see another S to see if the grill is original - I suspect it is though so that's probably not the issue ;-)
Only slight confusing thing there was "smack on the white line - 90 degrees" as mine has a 90 on the gauge then above that it has the white line.
I've set the Kenlowe up to come on as the needle is obscuring the top of the 90 and it does that, dropping it back to 90 just nicely, so I assumed that was somewhere in the 95-100 range to trigger the fan.
The fact that it needs to do it on the motorway too is the primary concern.
Hopefully I'll get a chance to sort this in the next week or two, but the car's still perfectly usable as it is so it's not massively problematic.
Thanks for the help...
I do need to see another S to see if the grill is original - I suspect it is though so that's probably not the issue ;-)
Julesprivate said:
Only slight confusing thing there was "smack on the white line - 90 degrees" as mine has a 90 on the gauge then above that it has the white line.
Sorry, wrote that from memory (of a Goldfish) while at work, whatever that white line represents is where the needle sits no matter what the weather or speed.From my experience of bonnets (and I've had a little but that's another story) various styles of mesh were used over the years from very fine, maybe 1/8" holes to very coarse, 1/2" + holes.
Just looking at car builder solutions site, is this http://www.cbsonline.co.uk/mobile/product/Radiator...
the correct rad cap? Say's it has a rubber upper seal.
Rob.
the correct rad cap? Say's it has a rubber upper seal.
Rob.
It's a 14lb std throw so it'll fit and do the pressurisation (albeit 1lb too low) but it doesn't say anything about it allowing for tidal flow/water recovery.
In theory, based on what I've read it's LIKELY that it is a recovery cap because of the upper seal BUT without it specifically saying so I wouldn't be certain.
I must admit I am tempted to get one of those, once I get a new thermostat in place...
In theory, based on what I've read it's LIKELY that it is a recovery cap because of the upper seal BUT without it specifically saying so I wouldn't be certain.
I must admit I am tempted to get one of those, once I get a new thermostat in place...
I had a problem last yr causing major cooling issues that resulted in a split header tank and Euro breakdown. Cause eventually tracked to a poor seal on the swirl pot - i have blanking cap on the swirl pot and pressure cap on the (brass MG) replacement header tank - there's a whole heap of debate which way round, so I'll just say it wokrs for me this way round.
Anyway, to get a good seal on the swirl pot I just nipped the lugs on the cap in a bit to pull the cap down tighter and used emery paper on the brass neck flat surface of the swirl pot. Car recently been to Spa and Nurburgring where temperature behaved impeccably with some very spirited driving in hot ambient temperatures - the "leak" on the swirl pot was very minor drips seeping slowly but the impact was massive which I would nt have believed.
I also struggled to find a good quality replacement cap but have fixed with existing caps.
Hope that helps rather than hinders.
Max.
Anyway, to get a good seal on the swirl pot I just nipped the lugs on the cap in a bit to pull the cap down tighter and used emery paper on the brass neck flat surface of the swirl pot. Car recently been to Spa and Nurburgring where temperature behaved impeccably with some very spirited driving in hot ambient temperatures - the "leak" on the swirl pot was very minor drips seeping slowly but the impact was massive which I would nt have believed.
I also struggled to find a good quality replacement cap but have fixed with existing caps.
Hope that helps rather than hinders.
Max.
Edited by Scoobimax on Tuesday 19th June 01:01
The good old "Can of Worms" eh?.
My very early S1 came to me with blanking cap on the swirl pot, and pressure cap on the (plastic) expansion tank.
This is in opposition to the bible, but seems to work well in my case.
My thinking is that if coolant expands into the overflow tank, when the system cools, how would coolant be able to return to the swirl pot if there is a pressure cap blocking it's path? A pressure cap is effectively a non-return valve.
My installation works for me, it never loses coolant, so if it ain't broke, don't try & fix it.
My swirl pot also has a small bore outlet below the top neck which has been blanked off, also a similar stub pipe on top n/sde of the radiator also blanked off.
Running temp is usually just below the white line, although I did have to back off a bit on the 4th lap of Spa when it got almost into the red. (But I had been spanking it a bit! ) This is the only time the temp has ever concerned me.
My intake mesh is very fine, but a previous owner has carefully drilled 4mm holes every 25 mm in a square pattern as per the bible suggestion, & it seems to work well.
Final thought..... is your air filter nice & clean?
HTH,
Glen.
My very early S1 came to me with blanking cap on the swirl pot, and pressure cap on the (plastic) expansion tank.
This is in opposition to the bible, but seems to work well in my case.
My thinking is that if coolant expands into the overflow tank, when the system cools, how would coolant be able to return to the swirl pot if there is a pressure cap blocking it's path? A pressure cap is effectively a non-return valve.
My installation works for me, it never loses coolant, so if it ain't broke, don't try & fix it.
My swirl pot also has a small bore outlet below the top neck which has been blanked off, also a similar stub pipe on top n/sde of the radiator also blanked off.
Running temp is usually just below the white line, although I did have to back off a bit on the 4th lap of Spa when it got almost into the red. (But I had been spanking it a bit! ) This is the only time the temp has ever concerned me.
My intake mesh is very fine, but a previous owner has carefully drilled 4mm holes every 25 mm in a square pattern as per the bible suggestion, & it seems to work well.
Final thought..... is your air filter nice & clean?
HTH,
Glen.
If the system isn't pressurising properly, the boiling point will be all over the place, and the temperature will be erratic. It needs the pressure to run withing the designed temperature limit. You really need to sort out the cap and make sure the system is pressurising properly, before you try to diagnose anything else, or go dismantling stuff and trying to fix a problem that maybe isn't there.
tvrgit said:
If the system isn't pressurising properly, the boiling point will be all over the place, and the temperature will be erratic. It needs the pressure to run withing the designed temperature limit. You really need to sort out the cap and make sure the system is pressurising properly, before you try to diagnose anything else, or go dismantling stuff and trying to fix a problem that maybe isn't there.
It's definately pressurising properly.... Unfortunately the proof of that is the scalded right arm, chest and face I have as a result of taking the cap off when the car was still pressurised and the collant close to boiling point.My own STUPID fault but OMG does it hurt!
I mistook a "lifted" pressure cap (the one without the rubber seal on top) for a "loose" pressure cap, assumed there was no pressure and took it off.....BAD mistake.
glenrobbo said:
The good old "Can of Worms" eh?.
My very early S1 came to me with blanking cap on the swirl pot, and pressure cap on the (plastic) expansion tank.
This is in opposition to the bible, but seems to work well in my case.
My installation works for me, it never loses coolant, so if it ain't broke, don't try & fix it.
My swirl pot also has a small bore outlet below the top neck which has been blanked off, also a similar stub pipe on top n/sde of the radiator also blanked off.
Running temp is usually just below the white line, although I did have to back off a bit on the 4th lap of Spa when it got almost into the red. (But I had been spanking it a bit! ) This is the only time the temp has ever concerned me.
My intake mesh is very fine, but a previous owner has carefully drilled 4mm holes every 25 mm in a square pattern as per the bible suggestion, & it seems to work well.
Final thought..... is your air filter nice & clean?
HTH,
Glen.
Thanks Glen, that's excellent, that describes my setup to a T. I'll probably drill some holes in the mesh to see if that helps too. I'll admit I haven't checked the air filter, I'll do so tonight.My very early S1 came to me with blanking cap on the swirl pot, and pressure cap on the (plastic) expansion tank.
This is in opposition to the bible, but seems to work well in my case.
My installation works for me, it never loses coolant, so if it ain't broke, don't try & fix it.
My swirl pot also has a small bore outlet below the top neck which has been blanked off, also a similar stub pipe on top n/sde of the radiator also blanked off.
Running temp is usually just below the white line, although I did have to back off a bit on the 4th lap of Spa when it got almost into the red. (But I had been spanking it a bit! ) This is the only time the temp has ever concerned me.
My intake mesh is very fine, but a previous owner has carefully drilled 4mm holes every 25 mm in a square pattern as per the bible suggestion, & it seems to work well.
Final thought..... is your air filter nice & clean?
HTH,
Glen.
Just to be 100% clear, mine runs at just below the white line too, the kenlowe kicks in and maintains that at all times. My ONLY concern is that the fan has to help out even ay motorway speeds which seems odd, but other than that the coooling system is "working", I just think it's struggling unnecessarily and want to introduce a better safety margin.
I'm off to put some more aloe vera on my arm and face now - what a total prat (me that is!)
Julesprivate said:
tvrgit said:
If the system isn't pressurising properly, the boiling point will be all over the place, and the temperature will be erratic. It needs the pressure to run withing the designed temperature limit. You really need to sort out the cap and make sure the system is pressurising properly, before you try to diagnose anything else, or go dismantling stuff and trying to fix a problem that maybe isn't there.
It's definately pressurising properly.... Unfortunately the proof of that is the scalded right arm, chest and face I have as a result of taking the cap off when the car was still pressurised and the collant close to boiling point.My own STUPID fault but OMG does it hurt!
I mistook a "lifted" pressure cap (the one without the rubber seal on top) for a "loose" pressure cap, assumed there was no pressure and took it off.....BAD mistake.
"some pressure" and "proper pressure" might be two different things, and unless you are certain that there is no leakage of pressure or coolant whatsoever, the system won't work as it was intended to.
tvrgit said:
You asked if the cap should have a rubber seal. The answer to that question is yes. Yours doesn't. It's unlikely to be pressurising properly. Even a very low pressure will result in an eruption if you take the cap off as the depressurised coolant instantly boils.
"some pressure" and "proper pressure" might be two different things, and unless you are certain that there is no leakage of pressure or coolant whatsoever, the system won't work as it was intended to.
Good point, and after all that's the quickest/easiest thing to try (a new pressure cap). I have one on order so I'll put that on as soon as it arrives."some pressure" and "proper pressure" might be two different things, and unless you are certain that there is no leakage of pressure or coolant whatsoever, the system won't work as it was intended to.
glenrobbo said:
My thinking is that if coolant expands into the overflow tank, when the system cools, how would coolant be able to return to the swirl pot if there is a pressure cap blocking it's path? A pressure cap is effectively a non-return valve.
Glen.
The proper cap with the upper rubber seal has a return valve in the end to allow the system to suck the water back in as it cools. Works well provided everything is sealed properly.Glen.
Rob
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