The symptoms don't match the coolant loss.
Would disagree mate, he said that the cap was ok to 16 and then it increases pressure above this when revving (he stopped at 19 at a couple of thousand rpm - and that was without the engine under load.. There is no evidence at all for coolant into the cylinder (quite the opposite). A small leak in the cylinder to coolant most often is only one way at the beginning due to the huge pressure differential. Also the bubbles in the previous test would confirm it - AND the low 3 pot reading. AND the over-pressurising when revving.
Hi Nodge mate,
I can quite understand your hesitancy after an episode like that ! - we have all been 'burnt' when #making the call#I kind of agree and what you say is valid for most engines. However I have been caught out by similar bubbling in the coolant before on the KV6. I was asked to give a second opinion and possibly repair a suspected HG leak.
On this KV6, I could find no external leak to speak of and the pressure cap wasn't blowing, but it was loosing similar amounts of coolant as the OPs car. I didn't do a compression test iirc, but the HG was blamed for the coolant loss by the garage that looked at it before me. After I'd removed the engine for a strip down, I was taking the thermostat and link pipe off, when I spotted a small nick in the link pipe O ring. The link pipe is on the suction side of the water pump. So a small hole here will draw air into the collant jacket and out the top bleeder pipes, but only when the cap is off. With the cap fitted, a small drip would have been evident under the pipe, but as the engine is over 100°C this drip simply evaporated off almost instantly, so I didn't spot it
I spoke to the owner, suggesting that the HG might not be the issue. But as he had got all the parts, said replace the HGs anyway. I rebuilt the engine and fitted a new thermostat and it's pipework.
The engine ran perfectly for the next 5 years that I know of.
So I'm generally more couscous before jumping on the "it's the head gaskets mate" waggon.
- what you say is quite enlightening and logical, and we can only go off what someone has said and NOT something we seen or done, which makes thing extremely hard to pin down. - I spent 8 years of my life on the Isles of Scilly. .. (and yes, I have heard all the jokes)
I can quite understand your hesitancy after an episode like that ! - we have all been 'burnt' when #making the call#
We do have some option though.
Using a catch tank will show coolant output from the coolant header - and not elsewhere. A definitive test is to rev at cold and literally smell the escaping bubbles - if definite combustion smell I would have no hesitancy at making the call without fear of being 'burnt'. I would also make the call on fluid loss (with all the other symptoms) via the coolant expansion tank.
Regards Nodge,
Joe
ps, how close are you to the 'pointy end' of the UK -
Hello Nodge,
? - I certainly had lots and lots and lots of that - well, it WAS the 70's
I kind of agree and what you say is valid for most engines. However I have been caught out by similar bubbling in the coolant before on the KV6. I was asked to give a second opinion and possibly repair a suspected HG leak.
On this KV6, I could find no external leak to speak of and the pressure cap wasn't blowing, but it was loosing similar amounts of coolant as the OPs car. I didn't do a compression test iirc, but the HG was blamed for the coolant loss by the garage that looked at it before me. After I'd removed the engine for a strip down, I was taking the thermostat and link pipe off, when I spotted a small knick in the link pipe O ring. The link pipe is on the suction side of the water pump. So a small hole here will draw air into the coolant jacket and out the top bleeder pipes, but this is only when the cap is off. With the cap fitted, coolant pressure would stop air being drawn in and small drip would have been evident under the pipe, but as the engine is over 100°C this drip simply evaporated off almost instantly, so I didn't spot it
I spoke to the owner, suggesting that the HG might not be the issue. But as he had got all the parts, said replace the HGs anyway. I rebuilt the engine and fitted a new thermostat and it's pipework.
The engine ran perfectly for the next 5 years that I know of.
So I'm generally more couscous before jumping on the "it's the head gaskets mate" waggon.
One way to isolate if water is coming from cap or otherwise is to fit a 'fluid indicator' to the expansion tank. It could be kitchen towel /paper (not sue what the correct name is in Canada) around the expansion tank and screw top area to catch any coolant / fluid that may be being ejected from there. The colouring in the antifreeze will help, also the paper, even if it dried (unlikely) would show obvious evidence of having been saturated.
- well kind of - depending WHERE it was) is that the pressure rose to at least 19psi (before you intervened and stopped the testing)with your coolant pressure tester on. (hence a sealed system) with pressure continuing to rise it would indicate an internal pressurisation of a closed system which can only be coming from the combustion process. the leak may be elsewhere, however the pressure is still rising above normal.
