Help with identifying wether the head gasked is leaking gas into the coolant

[Bakdraft007]

My stag seems to be running fine, but suddenly the Expansion tank keeps emptying. This might be the head gasket leaking exhaust gasses into the cooling system (well most likely) but maybe there are other causes.

• I do not see any leaks anywhere on the engine
• The car floor is not showing any fluid
• There does seem to be coolant leaving the tank to a collector bottle

This is a new phenomena, As mentioned that engine is running good in every way, temperature normal, power normal engine as silent running as ever.

I saw in a previous post this kit, DA YUAN YT105861 - search on ebay (by Jbuckl) was mentioned to test the pressure, but I was wondering how that kit worked to see if was worth the investment to try it. It says it can identify the side of the block or even the cylinder causing the issue... but how?

As the engine is so sweet, I do not want to tear it apart or equally ignore it.

Yesterday I topped up the expansion bottle only for it to go low (indicator light) after 1 hour of driving, so there is my concern.

Its a Mark 1 with an exapnsion tank fitted for 2 years with no issues.

Any help appreciated

Dave

[Goldstar]

You don’t need to spend £60 to test the pressure. Bit of hose with a Schaefer valve attached to the rad and pumped up with a bike pump. I think DJT posted a picture of his set up not long ago

you can also get a sniffer test kit for about £15 which will change colour if you have combustion gas in the coolant

[Bakdraft007]

You don’t need to spend £60 to test the pressure. Bit of hose with a Schaefer valve attached to the rad and pumped up with a bike pump. I think DJT posted a picture of his set up not long ago

you can also get a sniffer test kit for about £15 which will change colour if you have combustion gas in the coolant

Yes, I saw DJT's post, I I might go that way, I was more curious about whether the other system could indeed identify a block side and even a particular cylinder as I could not see how with the kits given.

This is how the tank looked this morning
IMG_0765.jpg

so it looks like some has left the bottle to the collector bottle..... but yet,

when I went to the collector bottle it was not overflowing, but fairly full.. to the neck say. So I toped the tank back up with the collector bottle so it now looks like

IMG_0766.jpg

So at least I have a way of monitoring if and how much leaves the expansion tank....

Strange as I added about 800ml yesterday to the expansion tank

A bit confused really..... maybe I just need to monitor it ... and report back

[DJT]

I nursed my car along for a year or so with it blowing coolant out of the header tank if I exceeded about 2500rpm. A sniffer test did not pick up any combustion gases in the coolant. I eventually took the heads off and fitted new BGA gaskets. Problem solved.

[jbuckl]

You don’t need to spend £60 to test the pressure. Bit of hose with a Schaefer valve attached to the rad and pumped up with a bike pump. I think DJT posted a picture of his set up not long ago

you can also get a sniffer test kit for about £15 which will change colour if you have combustion gas in the coolant

How will the improvised equipment indicate the pressure?
Afaiaa a schraeder valve is good for 120+ psi at least.

[DJT]

How will the improvised equipment indicate the pressure?
Afaiaa a schraeder valve is good for 120+ psi at least.

If you read the post I wrote a while back I used a bicycle pump with a built in pressure gauge. Only needed a few strokes to get 20psi.

[Goldstar]

How will the improvised equipment indicate the pressure?
Afaiaa a schraeder valve is good for 120+ psi at least.

Buy a pump with a gauge

[jbuckl]

My bad….Missed the gauge in the picture. My cycling days are some time back!

[Goldstar]

My bad….Missed the gauge in the picture. My cycling days are some time back!

[trunt]

Are you sure the pressure cap is ok? I.e. Sealing properly and not releasing at a lower pressure than spec.

[richardthestag]

Pressure cap is a good call. I have had issues with some of these not seating tightly to the inner face of the neck.

Block test would be my Forum test - "google" BT-500 block test for the set up which is quick and easy to use.

before that however I would brim the expansion tank, leave the cap off and run the engine. it will overflow as the coolant expands, that bit is normal, you are looking for bubbles.

Could be that there is an airlock in the system also and not wishing to tech "granny to suck eggs" but are you sure that the excess fluid is not just the expansion tank finding it's correct level.

It is after all a long running issue with these type of expansion vessels that the maximum fill level is not always clear.

[Bakdraft007]

Pressure cap is a good call. I have had issues with some of these not seating tightly to the inner face of the neck.

Block test would be my Forum test - "google" BT-500 block test for the set up which is quick and easy to use.

before that however I would brim the expansion tank, leave the cap off and run the engine. it will overflow as the coolant expands, that bit is normal, you are looking for bubbles.

Could be that there is an airlock in the system also and not wishing to tech "granny to suck eggs" but are you sure that the excess fluid is not just the expansion tank finding it's correct level.

It is after all a long running issue with these type of expansion vessels that the maximum fill level is not always clear.

Thanks Trunt and Richardthe stag. The pressure cap thing has been on my mind. I seem to think that there are two caps available 13lb for M1, and 20lb for mK2. I have an engine that has repairs in the past that makes it a bit of both, so what to do? I think I ended up putting a 13lbf on the expansion tank as I did not want to deliberately have too much pressure build up and damage the gaskets. The cap is so corroded I could not read the pressure...but I believe its 13lb.

So do you guys think it could simply be I have the wrong cap on? I am not sure which part (the pump or passageways?) generates the higher pressure, or is it that the MK1 was not did not have the sealed expansion tank that the MK2 has? Its extremely easy for me to try, as the cap on the radiator (mk1) to seal off the radiator is a 20lb and the expansion outlet is blocked off at that point,so I can just swap them around.

The cap seals well as I know that after it cools, even after months of running, you can always hear an air rush in or out as the cap is removed.

I do not think there is an airlock as its been 2 years of no issues since the last drain down and antifreeze change. The heater works fine and I never turn it off, even in the summer. The most I do with the heater is close off the airflow to stop me roasting in the summer.

Normally I fill the expansion tank 3/4 and that has been fine for 2 years, with no change in level. This dropping is suddenly new.

I can try running it without the cap to see how it looks, and report back. But it maybe that if it only leans air into the coolant under high load high revs, thats difficult to do statically.

Dave

[marshman]

Thanks Trunt and Richardthe stag. The pressure cap thing has been on my mind. I seem to think that there are two caps available 13lb for M1, and 20lb for mK2. I have an engine that has repairs in the past that makes it a bit of both, so what to do? I think I ended up putting a 13lbf on the expansion tank as I did not want to deliberately have too much pressure build up and damage the gaskets. The cap is so corroded I could not read the pressure...but I believe its 13lb.

So do you guys think it could simply be I have the wrong cap on? I am not sure which part (the pump or passageways?) generates the higher pressure, or is it that the MK1 was not did not have the sealed expansion tank that the MK2 has? Its extremely easy for me to try, as the cap on the radiator (mk1) to seal off the radiator is a 20lb and the expansion outlet is blocked off at that point,so I can just swap them around.

The cap seals well as I know that after it cools, even after months of running, you can always hear an air rush in or out as the cap is removed.

I do not think there is an airlock as its been 2 years of no issues since the last drain down and antifreeze change. The heater works fine and I never turn it off, even in the summer. The most I do with the heater is close off the airflow to stop me roasting in the summer.

Normally I fill the expansion tank 3/4 and that has been fine for 2 years, with no change in level. This dropping is suddenly new.

I can try running it without the cap to see how it looks, and report back. But it maybe that if it only leans air into the coolant under high load high revs, thats difficult to do statically.

Dave

If it is in that state change it anyway. Low cost and rules it out. Also it could be that the cap is not allowing liquid to be sucked back in from the overflow bottle, hence the "feeling" of pressure/vacuum when you release the cap.

Later Stags had a 20 lb/sqin cap.

[DJT]

Pressure cap on radiator = 13psi
Pressure cap on expansion bottle = 20psi

If it is as bad as you say, fit a new one. Buy from a reliable source - SOC Spares or LD Parts for example.

[Bakdraft007]

If it is as bad as you say, fit a new one. Buy from a reliable source - SOC Spares or LD Parts for example.

Strangely it was brand new 2 years ago...

image.png
It was this one from LD parts... and as you can see in the picture on their website did not look great from new You can see how it looks now in the photo of the header tank above

Still no problem swapping it with the other one