Technical Head Gasket Failed

[thornebt]

Thanks for a very comprehensive answer. I just need to source a compressor. I've got a cordless tyre pump but it's noisy so may drown out any hissing sounds. I don't think I will have any problems with the compressed air turning the engine over as there's no compression on that cylinder.

 

[Pugglt Auld Jock]

Thanks for a very comprehensive answer. I just need to source a compressor. I've got a cordless tyre pump but it's noisy so may drown out any hissing sounds. I don't think I will have any problems with the compressed air turning the engine over as there's no compression on that cylinder.

A DIY type tyre inflator will not be able to supply anything like the volume of air needed. Also you'll need something with a reservoir, something along these lines might work: https://www.machinemart.co.uk/p/clarke-bandit-v--42cfm-8l-1hp-air-compressor-2/ and you'll probably find generic examples more cheaply on the likes of ebay. However, having owned one myself, these small direct drive (direct drive being where the compressor pump is driven directly from the output shaft of the electric motor - so no belt and pulleys - are VERY noisy when running so you need something with a big enough reservoir so the motor isn't running continuously or you won't her anything over the noise of the compressor running!

Edit. If you think your cordless pump is noisy just wait 'till you hear a direct drive compressor running! By the way, I should have said another thing you can listen for when doing a leak down test is to stick a "listening tube" into the spark plug hole of cylinders adjacent to the cylinder you are pressuring. If you hear a hiss then the gasket between that cylinder and the one being pressurized is breached. I mention this because it's very possible to get a gasket failure between cylinders (the gasket is generally very thin here) without it breaking into the cooling system - so you won't get bubbles in the radiator/header tank.

 

[koalar]

What's the results of test in post 16

Photo of all 4 plugs

Video of it running

How long have you had the car, did all the issues start at once

We have conflicting information

Nice clean pink coolant, nice clean explanation tank

Misfire cylinder 3, compression fine cyl 3

No compression in cylinder 2 but misfire in 3

Head gasket can give coolant issues but not zero compression

Valve will give zero compression but not a coolant issue

The compression should be over 200 psi normally 220 but we are at 180, I never bother opening the butterfly and still give valid results, I don't believe it's further enough out to be timing !

Does depend on the state of the battery though

Given it's wrong on all 4 cylinders I think it's highly likely the compression test is suspect and it's not getting a good enough seal, I use the cone type adapter on the 8v engines but I don't think it's an option on the 16v

 

[thornebt]

What's the results of test in post 16

Photo of all 4 plugs

Video of it running

How long have you had the car, did all the issues start at once

We have conflicting information

Nice clean pink coolant, nice clean explanation tank

Misfire cylinder 3, compression fine cyl 3

No compression in cylinder 2 but misfire in 3

Head gasket can give coolant issues but not zero compression

Valve will give zero compression but not a coolant issue

The compression should be over 200 psi normally 220 but we are at 180, I never bother opening the butterfly and still give valid results, I don't believe it's further enough out to be timing !

Does depend on the state of the battery though

Given it's wrong on all 4 cylinders I think it's highly likely the compression test is suspect and it's not getting a good enough seal, I use the cone type adapter on the 8v engines but I don't think it's an option on the 16v

Post 16 isn't my engine. It's posted by someone else.

I'm away in my motorhome at the moment so no access to the car. Doing a proper conversion the readings of approx 13psi are closer to 188psi. That's with the engine cold so would be higher with warm engine. Readings were consistent on three cylinders but gauge needle didn't even flicker on cylinder 2.

Owned the car for a few years. Problems happened a few days ago. I'm going to source a compressor with a tank and see where that takes me.

 

[thornebt]

I borrowed a compressor and injected air into the cylinder with the engine at TDC. Obviously both valves should be fully closed at that point but the air is very powerfully coming out the air filter pipe.

I don't think there can be any doubt that there's some sort of failure of the inlet valve / valve seat. I rotated the engine round to TDC a second and third time to make sure and got exactly the same result. To make absolutely sure I rotated the engine by pushing the car in sixth gear whilst injecting air. There was a slight change in the sound of the air coming out during this but it was leaking throughout the whole process.

I will remove the cylinder head extension (top half of the cylinder head) and I'm sure I will then see what has happened to the inlet valve.

 

[varesecrazy]

I borrowed a compressor and injected air into the cylinder with the engine at TDC. Obviously both valves should be fully closed at that point but the air is very powerfully coming out the air filter pipe.

I don't think there can be any doubt that there's some sort of failure of the inlet valve / valve seat. I rotated the engine round to TDC a second and third time to make sure and got exactly the same result. To make absolutely sure I rotated the engine by pushing the car in sixth gear whilst injecting air. There was a slight change in the sound of the air coming out during this but it was leaking throughout the whole process.

I will remove the cylinder head extension (top half of the cylinder head) and I'm sure I will then see what has happened to the inlet valve.

Late to this.. ,

Ok so you've had dropping coolant
(any mayo in the valve cover / filler cap? )
Should be LOTS if it's a HG Issue


BUT if you've dropped a valve.. How would that drop the coolant?


May be worthwhile checking valve clearances at this point

My experience is with 1.1 and 1.2 basic FIRE. Did a 12v Brava once..

NOT Touched a 1400..

 

[thornebt]

Late to this.. ,

Ok so you've had dropping coolant
(any mayo in the valve cover / filler cap? )
Should be LOTS if it's a HG Issue


BUT if you've dropped a valve.. How would that drop the coolant?


May be worthwhile checking valve clearances at this point

My experience is with 1.1 and 1.2 basic FIRE. Did a 12v Brava once..

NOT Touched a 1400..

There's no emulsification inside the oil filler cap. I agree the inlet valve problem doesn't explain the loss in coolant. I'll report back when I've removed the top half of the cylinder head. It may take some time as I'm busy with some other stuff these days.

Thanks for your help so far everyone. This is a great forum.