Griffith, pressursing coolant!! Help please
Discussion
Hi everyone, first time posting on pistonheads! I have only owned my Griffith 500 for a little over a month but have a strange problem with the coolant. When I brought the car the expansion bottle cap was leaking when the car got hot and would leak coolant. I replaced the cap and all seemed well. I bleed the system and hoped no more problems would occur. After returning from some drives out I would notice a gurgling sound coming from the expansion bottle and swirl pot. Just thought this was air pockets making there way out. I filled the expansion bottle exactly on the weld line half way up, but after checking it the next day once it had cooled it had raised about 2 inches. Left it alone and done another 150 miles, checked again and the coolant escaped as soon as i undone the cap, it was under pressure and right up to the top of the expansion bottle. I have no other symptoms, no oil contamination, no coolant contamination, no overheating problems (car runs at 80-85 on warm day, fans on at 90), and no steam from the exhaust. What is causing the coolant level to rise? Surely head gasket would show other symptoms. The car does take a long time to reach correct temperature when its cool, sometimes never making it( some evenings it stays at 65-70). Could a stuck open or missing thermostat cause this? Thanks for your help, its a long thread to read!!!
Take it to a garage who can test the coolant pressure, the cap is a TVR/VW. Really eay to test just screw the pressure tester on to the TVR/VW alloy tank and run the car up to temperature and watch what psi it gets up too and if the pressure rises and falls fast. Could just be an air lock.
Mine behaved the same after a rad replacement. I would expect the car to get very hot if combustion gases were escaping into the coolant. Yours stays cool so I'd say it's too early to expect the worst.
I'd persevere with the bleeding routine – I had to do mine more than once to stop the problem. Try raising the nose of the car a little before releasing the bleed screw on top of the rad and don't let the level in the swirl pot drop too low before you retighten the rad bleed screw and top up the swirl pot.
Now the coolant level sits right on the weld line and never moves but I've heard that every car is different. The trick is to establish the level your car likes and avoid topping up beyond that.
Good luck.
I'd persevere with the bleeding routine – I had to do mine more than once to stop the problem. Try raising the nose of the car a little before releasing the bleed screw on top of the rad and don't let the level in the swirl pot drop too low before you retighten the rad bleed screw and top up the swirl pot.
Now the coolant level sits right on the weld line and never moves but I've heard that every car is different. The trick is to establish the level your car likes and avoid topping up beyond that.
Good luck.
Hi, thanks for all the advice, went to see Leven technology today and explained my problem to them. Very helpful, seemed to thick it was just a bad air lock caused by leaking expansion cap and i did have a little leak on rad bleed screw. Just fitted new thermostat 74 degree (old one was stuck open), new otter switch (slightly lower temp) and new gauge sender. Was advised a slightly different way of bleeding air then posted on here. It goes, fill swirl pot, half fill expansion bottle, (can bleed rad at this point and top up if ness), then replace brass screw on swirl pot and heaters to hot. Start engine with expansion bottle cap off. You can then see coolant expanding slightly and bubbles from air being pushed out by thermal expansion in swirl pot. Continue this until bubbles stops and stop engine. The level in expansion bottle will drop as coolant cools and contracts, keep topping bottle up!!! This may need to carried out several times including drives in between to dislodge air, but im assured its the best way to bleed and not introduce any more air!!! Lets hope this works and no more problems
On my car (a '97 Griff 500), there is a short length of blanked off small bore hose coming out of the inlet manifold just behind the oil filler cap beside the L/H rocker cover. This I imagine is the hose that would go to the unused spigot on the throttle body when the throttle body was heated in the engine's original application. I have found this to be a useful bleed point and have always found that after refilling the system from empty that it needs bleeding more than once. The water level usually settles to about 1/3rd of the way up the expansion tank.
Right, after fitting new thermostat, otter switch (both lower temp) and religious bleeding I still have the coolant under a lot of pressure once the car has cooled the following day! and the level rises from about half full to completely full. And this is with a new pressure cap!! Car is now with RPI engineering to have the heads off to see if pressure was escaping past head gasket and pressurising the coolant!! Ill keep you updated
moorcroft said:
Car is now with RPI engineering to have the heads off to see if pressure was escaping past head gasket and pressurising the coolant!! Ill keep you updated
WTF? That's an extremely expensive way to diagnose a problem that could be detected in seconds with a block tester. You would also expect to see scum in the coolant, and massive frothing from the header tank if you rev it with the cap off. This sort of problem is very well known and easy to diagnose and there's really no need at all to start paying people to take stuff apart until you have a confirmed diagnosis.The gasket has not necessarily completely failed. If it is tin or copper it is able for some pressure to escape above or below the gasket and escape (See www.v8engines.com), block test was carried out and showed positive. Some scum was once seen in header tank but as it regularly dumped/overflowed then this was hard to check. Also with recent replacement of thermostat, otter and sender meant system had fresh coolant.
moorcroft said:
I mean presence of gasses. There is nothing else then could be repeatedly pressurising the coolant no matter on how often it is bled.
That's pretty conclusive then. I may have missed you telling us this earlier, but if you've got HGF or a slipped liner (as this block test result indicates) you're wasting your time trying to bleed the system or look for problems with the fill level or pressure cap etc.
GreenV8S said:
moorcroft said:
I mean presence of gasses. There is nothing else then could be repeatedly pressurising the coolant no matter on how often it is bled.
That's pretty conclusive then. I may have missed you telling us this earlier, but if you've got HGF or a slipped liner (as this block test result indicates) you're wasting your time trying to bleed the system or look for problems with the fill level or pressure cap etc.
Good to see you posting your invaluable knowledge fella i for one appreciate it
i have just had same issue,but now diagnosed as a cracked/slipped liner and damage to big end /piston and head...
it seems that coolant in my engine was pressurized due to water ingress to a rear cylinder causing damage...
It would be interesting if others who have suffered this problem would post to let us know if this is a common problem.
Mark
it seems that coolant in my engine was pressurized due to water ingress to a rear cylinder causing damage...
It would be interesting if others who have suffered this problem would post to let us know if this is a common problem.
Mark
Sumoone, It would seem that your water jacket in the block must have spilt. These are very close to the cylinders due to the extra bore diameter that TVR took the 5L out too. This is a known problem but usually effects higher mileage cars. How many miles does yours have. Once the block is cracked (porous) water escapes and is stuck between the block and the liners. This acts as lubricate and allows the liner to slip. Water can then enter chamber and cause piston and head damage. I would say your coolant pressure has come from localised boiling due to escaping coolant rather then piston pressurisation, possibly. Was your oil contaminated? Water escaping the block inbetween the block and liner can also travel down into the bottom of the vee (where the crank is) and cause damage to the crank.
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