Possible Head Gasket Failure

[crazylegs]

i use a sniff test as well, as paul states it is not 100% accurate but for most its the best we have.
if you could knock up one of your special tools when you have a minute you biscuit tin would be overflowing for a month or two.

[cartledge_uk]

i use a sniff test as well, as paul states it is not 100% accurate but for most its the best we have.
if you could knock up one of your special tools when you have a minute you biscuit tin would be overflowing for a month or two.

Its called a leakdown test.

There is a variation on pauls tool thats easier (but a bit more expensive) to make.

Take one compression tester, remove the gauge, fit a T piece, add the guage on, and then add an airline adapter on.

That way you can not only measure what you put in, but you can measure the "leakage"

Listening to where the air escapes can also tell you if valves are gone and rings.

Best method ever

[ligertigon]

Ok slightly off topic, but....

If you use pauls method, and put a condom over the inlet manifold stub, and another over the exhaust.
It might also tell you if you have leaky inlet or exhaust valves.

However, would I be right in thinking that if there is a hairline crack on the cylinder bore under the piston rings at tdc, this won't show itself with the pressure test? yet might mimic a failed hg

[PW@Woodsport]

However, would I be right in thinking that if there is a hairline crack on the cylinder bore under the piston rings at tdc, this won't show itself with the pressure test? yet might mimic a failed hg

Ah right,how we get around this one is to slip the timing belt off so that the valves are always shut,carry out my pressure test with the piston at TDC (checking the gasket) and then carry out the same test with the piston at BDC.... if it fails the second test but passes the first then it has a cracked block,all without ever having to remove the head,pretty simple really.

As promised here is the PW SST (the official new name for it lol )



An airline end,a section of tube,and a drilled out spark plug all welded together.... 100% test results every time.

[ligertigon]

However, would I be right in thinking that if there is a hairline crack on the cylinder bore under the piston rings at tdc, this won't show itself with the pressure test? yet might mimic a failed hg

Ah right,how we get around this one is to slip the timing belt off so that the valves are always shut,carry out my pressure test with the piston at TDC (checking the gasket) and then carry out the same test with the piston at BDC.... if it fails the second test but passes the first then it has a cracked block,all without ever having to remove the head,pretty simple really.



QED

[PW@Woodsport]

mr2mk1chick wrote:

I guess with most faliures the other techniques are usually adequate.

On the contrary im afraid,mr2 gasket failures are never of the huge drama events that occur on fords and vauxhalls,in other words in almost every case they fail as a result of a very fine hairline break in the gasket between number 4 cylinder and the frontmost water jacket.This hairline break is VERY hard to diagnose just using a compression test or sniff test primarily because it offers no significant drop in compression to be able to tell.Also the sniff test can also miss a break this fine.

I think ive only maybe seen one or maybe two cars in the last 10 years that had a serious breach that resulted in the engine running very rough and having the big clouds of steam out of the exhaust etc.... The majority,and id say an easy 99% of them,exhibit the very fine break in the HG....hell ive ever driven an mr2 for months with a known break and just kept on top of the coolant.

This method using the tool i made totally guarantees any ambiguity and can save a fortune in misdiagnosed costly head removals.

[Tiny]

Do you see this failure in the #4 cylinder only with the Toyota gaskets or is it more of a generic design flaw?

[cartledge_uk]

On the contrary im afraid,mr2 gasket failures are never of the huge drama events that occur on fords and vauxhalls,

Tell that to the poor people on the m40 that 4 years ago had 15+litres of coolant coming at them over a 100m stretch in a steam cloud

[Paff]

Paul I must be unlucky. Both the engine that came in my spare car and the replacement one I put in created 10mm wide holes in the gaskets and ran really rough.

Never mind tho I'm slowly destroying all the 4age's

[PW@Woodsport]

Just goes to show that big gasket failures do happen i suppose,although its certainly not the norm for the 4age,they do tend to breach very gradually in the majority of cases.

[MRTWO]

I think ive only maybe seen one or maybe two cars in the last 10 years that had a serious breach that resulted in the engine running very rough and having the big clouds of steam out of the exhaust etc....

yep, thats exactly what happened to mine a couple of months ago though fortunately I was only half a mile from home. I wouldn't wish that on anyone.

Its all fixed now and running beautifully again

[Paff]

Hey Paul, you know when anything of mine breaks I like it to go in style, no point having small failures

[boyzdad]

Never mind tho I'm slowly destroying all the 4age's

I think you may have some help here, I am on my 3rd engine....... in 5 months

[cartledge_uk]

Never mind tho I'm slowly destroying all the 4age's

I think you may have some help here, I am on my 3rd engine....... in 5 months

*cough* i'm on 9 dead

(thats dead, not head gaskets etc)

[kaiowas]

*cough* i'm on 9 dead

(thats dead, not head gaskets etc)

I reckon you should get some little vinyl 4age's with crosses through them on the side of your car to mark your kills

[cartledge_uk]

*cough* i'm on 9 dead

(thats dead, not head gaskets etc)

I reckon you should get some little vinyl 4age's with crosses through them on the side of your car to mark your kills

That has been suggested before, I may have to do that

[Tiny]

Never mind tho I'm slowly destroying all the 4age's

I think you may have some help here, I am on my 3rd engine....... in 5 months

Yeah but your cars black so thats totally acceptable

[boyzdad]

Yeah but your cars black so thats totally acceptable

It'll be char-grilled Black if it keeps doin this!

Maybe I should name it "The dark (4A-GE) destroyer"

I reckon you should get some little vinyl 4age's with crosses through them on the side of your car to mark your kills [Mr. Green]

I really like that idea, I think I will have to do it, possibly stick them under the engine bay lid, just to remind me every time I open it........ it's only a matter of time

How about this for starters?

[Paff]

Ah have you managed to blow one up in 5 miles tho, Fitted it drove to work and it went on the way there

3 engines in under a week were in that car

[JMR_AW11]

Basically id ignore every single post on this thread,im serious,a sniff test is not 100% conclusive,and a compression test is even worse.I used to advocate the sniff test myself too years ago but it has proven to give inconclusive results.None of these methods work with any certainty.

These days the only way to be 100% sure is with a special tool we made for testing head gasket breaches.Its a spark plug that has been drilled out and the ceramic stem cut off,so basically its the threaded part,the nut part and a big hole through the centre.Then we got a 10mm steel tube about 8" long,welded that to the spark plug and then welded an airline end onto the tube.... so the new tool screws into the spark plug hole and with the engine rotated to TDC on whatever cylinder you wish to test (99.9% of the time its cylinder 4 on a mk1 thats gone) ,then supply 70psi of air to that cylinder and take the cap off the coolant filler point.

If there is even the slightest breach in the gasket the compressed air will get forced through it and fine bubbles will appear at the coolant neck.You can clamp the airline to watch them fade away or increase the pressure to watch them become more regular.... it really is a bombproof method of diagnosing it and we have tried every method!

Repeat the test on the other 3 cylinders...i guarantee you it will tell you one way or the other if its breached ,compression tests don't work because there is sometimes a 10% variation between the cylinders anyway.... and 10% might just be a hairline breach.

Hope that helps

On my red mk1 I had a HG scare about 5 years ago as I started losing coolant (turned out to be a leaky hose clamp)

The mechanic at Mr T did a similar thing to your test only he did it by running the engine and removing the metal coolant filler cap and looking for bubbles (both during running and also just after the engine was stopped). He also did the sniffer test and both were negative.

He reckoned he would see tiny bubbles due to the compression strokes causing combustion gases to be forced into the coolant.

The engine was hot when he took the cap off (engine running!) so I took a step back when he did that

amazingly the coolant didn't spurt out after the first big burp.

He did the sniff test at the filler cap as well with a warmed up engine and the engine running. It did look a bit scary TBH... (i.e. he didn't bother with the plastic expansion bottle)

Not one to try at home I guess (for obvious safety reasons) but he said that it was a fairly accurate test (but not 100%)