Ways to test for headgasket failure?

[Jim Bowen 1]

Been having a lot of coolant loss on the VR, thought it was other things, like tiny split in a hose etc, have fixed things but its still going down quite quickly. Like the header tank empty after 200-300 miles.

 

Am starting to wonder if its headgasket related?

 

Got no mayo or anything abnormal on oil cap, coolant in tank looks fine, no oil or anything odd in there.

 

But i do notice quite a bit of pressure in the system once its heated up, but is that normal anyway?

 

Drives fine, although i have noticed sometimes when i start it, it can be a little lumpy/misfire for a few seconds, although this could be electrical, ht leads/coilpack related.

 

Started to really bug me now. i can't see any coolant leaking that's obvious, i've only just rebuilt the engine bay back together and it got through coolant before this. Almost tempted to try one of them products you add to coolant to stop a leak (although always been against them sort of things)

[renson 0]

i'm sure you can test for a headgasket failure in a few ways. One is a pressure test on each cylinder another you can get a kit that samples the fluids from the collant system and changes colour if exhaust gases are present.

 

Some garages use the emissions tester to 'sniff' the coolant. This way is a right shoddy way though as what generally happens is they suck coolant up into the tester and then I have to fix them :(

 

Have you checked your carpets? could be the heater matrix or maybe the water pump is leaking? Maybe on a dry day chuck some cardboard down and leave it running and see where its dripping

 

I could be wrong but if you are loosing all of your coolant that quickly you should see some evidence of a headgasket failure like 'mayo' on the dipstick etc or overheating and it would run like crap.

[Jim Bowen 1]

I seem to have a lot of moisture/steam from the exhaust. Not sure if its the weather or not though.

 

All carpets seem dry. And struggling to see any leaks.

 

Might get one of them compression tools

[stuarttaylor37 13]

The symptoms you describe match exactly what mine was doing,no obvious leaks, no mayo on oil cap, no oil in coolant bottle, sometimes a lumpy start for a few seconds, very pressured (rock hard) hoses leading to the top one to the heater matrix splitting, steam in the exhaust and I had to start topping up more frequently.

I took it to a local VW specilist who reckoned he could smell G12 in the exhaust fumes even though it passed the emissions test. They took it apart and they were right, there were two places where coolant was leaking into the bores.

 

Good Luck

[james153 0]

Quite rightly so, id place the cardboard underneath and check the carpets.

 

But as stuart says it sounds a lot like a head gasket. the gasket can go in one of 3 ways;

oil to bore, results in smokey exhaust and potentially big oil pressure.

Oil to water, results in may and pressure of header tank

and finally, what it sounds like you have here, water to bore. will pressurise up the system and cause coolant loss with the symptoms you describe.

 

If you need a hand give me a shout, I'm only a couple of minutes up the road from you I think.

[vw rule 19]

Hello Jim,

 

if you are loosing coolant after only 200 or 300 miles and there are no signs of any leaks what so ever,

then yes it is possible that your engine is burning coolant.

But like Renson has said you should still check to see if the heater matrix is leaking,

as these normally only leak in side the car, normally on the front passenger side under the dash.

Plus Renson is correct regarding the engine block test procedure where a blue fluid is used,

if it changes from blue to yellow then that is normally means you've got a head gasket issue.

 

When using the block tester you may have to remove a little coolant so that the tester doesn't suck any coolant up,

like Renson has already kind of said,

plus there is a max line on the tester that you fill the blue fluid to,

other wise you'll just get a false reading from the tester.

The block tester is designed to sniff, smell for engine cylinder combustion fumes, and changes colour from blue to yellow.

 

The head gasket can blow in some places where it doesn't course the engine to misfire much or at all,

the gasket can blow between one or two water ports and so can seep in one or more of the cylinders,

as most of the water ports on the engine block & cylinder head are very close to the cylinders.

You could have a cracked cylinder liner or a crack in the cylinder head it's self,

this is how you could be loosing your coolant over 300 miles or so.

 

Also once the engine is up to running temp go to the back of the car and look at what is coming out of the exhaust tail pipe,

as there should be no black, grey or white smoke vapor, if you put your hand over the tail pipe for a second or two,

and then have a look at your hand there should only be very slight black soot,

if you see water droplets or water moisture on your hand or coming out of the tail pipe,

then again this is a sign that something could be wrong.

 

You've said that you can't see any water in the oil i.e (on the dip stick & oil filler cap)

and no oil in the coolant expansion tank, but have you sniffed, smelt the coolant in the expansion tank,

as it could smell of oil or fuel which again is a sign that you could be getting cylinder combustion fumes in the coolant,

which is how you get excessive pressure in the cooling system, leading to over heating issues and issues with loosing coolant with no visible leaks.

 

With your engine running on your drive if you let the car run up to temp, this may take around 15 to 20 mins from cold,

your coolant temp gauge should read around 90 degrees C, then your radiator cooling fan should cut in normally around 87 to 90C

 

Your temp gauge if it is reading 105 or 110 degrees C then you may have a problem with your cooling system,

as it shouldn't go up that high if your car is just running in your drive way, it should go to 90 to 95C max.

The temp gauge should drop down to around 78 to 84 degrees C once you are driving the car down the road,

if the gauge is still reading 90 or above then this means your cooling system is over heating.

 

Your coolant hoses from cold should feel soft you should be able to depress the hoses very easily,

once the cooling system is up to running temp you should still be able to depress the hoses slightly,

there should be some pressure in the hoses though once hot,

but if there's too much pressure this you will know as the hoses will feel almost rock hard,

this is the sign that the cooling system is over heating,

meaning that the water flow has stopped or the thermostat is still closed even though the coolant is at 87 to 90 degrees C,

or as mentioned above that you may have a cylinder head / gasket issue.

 

But like I say if you can't find any leaks anywhere from the cooling system,

then I'd say you may well have a internal engine issue.

 

Hope this helps.

 

Si :thumbleft:

[Jim Bowen 1]

Thanks for all the info guys, gives me plenty to digest.

 

Am getting the rock hard hoses, but found 3 minor leaks lastnight, one is the hose under the header tank, one is the sender on the rad and i noticed some pink on back of rad. Although was a new VW rad and still looks mostly like new, so will be gutted if that has sprung a leak. (but these leaks are tiny and not much evidence of coolant below them (which i would expect with the amount i'm losing)

 

Car is just about to hit 200,000miles and most of the engine is original still apart from timing chains, so it may be due some work.

 

Is there a guide to changing a headgasket? Is it worth looking out for a new head? Think i'm going to order another set of hoses as not too impressed with the samco ones.

 

---------- Post added at 10:06 AM ---------- Previous post was at 10:01 AM ----------

 

 

If you need a hand give me a shout, I'm only a couple of minutes up the road from you I think.

 

Nice one, yeah we aren't too far apart. Will let you know, hopefully i can manage.

 

Not sure whether to fix up the 12v or try a 24v, although most 24v lumps i find are over 100,000miles

[stuarttaylor37 13]

Thanks for all the info guys, gives me plenty to digest.

 

Am getting the rock hard hoses, but found 3 minor leaks lastnight, one is the hose under the header tank, one is the sender on the rad and i noticed some pink on back of rad. Although was a new VW rad and still looks mostly like new, so will be gutted if that has sprung a leak. (but these leaks are tiny and not much evidence of coolant below them (which i would expect with the amount i'm losing)

 

Again very similar to what I was finding, small leaks as hose/clamps started to fail....I fixed the one hose to the matrix that split....a few days later a small one started on the rad. Eventually I had to replace that as well although thankfully the matrix held........touch wood

[SamG40 0]

I've just finished a head gasket swap after steam coming out of the exhaust, coolant loss and a misfire for the first few minutes of the engine starting. In the end the steam coming out was in clouds so if it gets worse you'll know about it!

[owen g60 10]

I have the same issue.

Have had several hoses split in the past couple of weeks... Been replacing them with silicone ones as I go.

I've also been losing coolant a fair bit with no signs of a leak.

I get some smoke from the exhaust.. Has always been that way.

Some mayo on the oil cap, could be due to the amount of water that's been in the engine bay.

 

Will investigate when my new head and fitting kit turns up.

[Jim Bowen 1]

Just discovered the coolant is mainly coming out of the header tank. Can't tell if its the tank. Was a brand new one. Or if its coming out the little holes on the tank.

[james153 0]

That sounds like the pressure build up is causing it to come out of the header tank over flow. :(

[robo22sri 10]

Jim it might just be an air lock?

 

You did the hoses and rad not to long ago didn't you?

[vw rule 19]

Jim you could remove the thermostat as it does tend to restrict the water flow a little,

this is how the thermostat keeps the engine at a constant temperature,

which could also give you more pressure in the cooling system if the stat isn't working correctly,

which may lead to various hot spots around the engine or even air locks like Robo22sri has said.

So like I say with the stat removed the engine will run a lot cooler plus there will be a lot less pressure in the cooling system,

but you may find that you're burning a little more fuel as it's running that bit cooler.

But if there's still excessive pressure in the cooling system with the stat removed,

then you've 100% got a internal engine problem.

 

I would only run the engine short term with the stat removed,

as the engine won't be running really efficiently.

 

Si :thumbleft: