Technical Howto check for head gasket failure

[whatoncewas]

I'm looking for another car. It has to last at least 9 months. That is all I need it for really. If it lasts longer then that will be great, but not entirely essential. The purchase price will decide this requirement.

I went to see quite a few last week, all different makes/models.
I've scheduled viewing for a few Uno's this week. They all claim to be low mileage and well looked after and all have got some recent receipts for work carried out. Simple services to one with new head gasket work. MOT on all is at least 6 months. All also similar engines to the one I used to have. I've got a rough idea about what things to check from when I had my Uno. Any tips that I may have overlooked?

A failing head gasket feels like the worst problem I could end up buying. I don't think I would do that work myself, so the cost to pay a mechanic would kill my plan for cheap motoring. The one that had the head gasket work recently done is the oldest and most expensive. It would be my last choice purely on its price (and distance to get to view it).

What things should I check to make sure the head gasket is not failing? Overheating is the obvious one. The mayo on oil fillter cap.
Is it safe to have the coolant container (is it the overflow one on the FIRE engines?) open while the engine is running to check for bubbles?
Anything else?

Cheers guys.

 

[the mk1 kid]

The best way is to do a compression test however you may find the seller objects just out of ignorance more than anything else.

I'd let it idle until the fan cut in and out. If during this time it doesnt over heat i'd be pretty confident the HG is not on the way out. This isn't conclusive but and a NA engine thats being bought with a view of being economical (and driven slowly) i doubt you'd experince a problem. Forced inducted and driven hard - compression test all the way..

Tom

 

[whatoncewas]

As simple as that. Ok, great, thanks.

 

[luvduvs]

What things should I check to make sure the head gasket is not failing? Overheating is the obvious one. The mayo on oil fillter cap.
Is it safe to have the coolant container (is it the overflow one on the FIRE engines?) open while the engine is running to check for bubbles?
Anything else?

I agree - the compression test is probably the most effective way to check. If they won't let you do that then it sounds like the seller has something to hide.. Also look out for leaking coolant - leave the car running for at least five minutes and check the ground. Its safe to check for bubbles in the coolant container with the engine running (but not with the radiator cap off - you'll burn yourself!). And obviously if the coolant level drops then that's a problem. (Not sure if this is relevant, but also check the exhaust for liquid being spit out)

 

[Stephan1]

hmmm lets shed abit more light. fiat you say. F.I.R.E. engine it is you say. well the first thing to check when you get to the car has the car been running before you got there if so walk away as this would indicate a starting problem. but if its stone cold with out touching the pedal start the car it should idle smoothely on start up. if not walk away. so lets say its started up great and is idleing smoothe now let the car warm up and go for a spin what you are looking for is smoothe running all the way. test drive the car for atlest an hour after your test drive let the car settle for 15 mins or so and check the oil cap and rad filler for any gunk also check the millage is genuine as fiats require cam belt and water pump change at 50k miles so realy in essence if in doubt walk away as you the buyer is king so if your not sure walk away.

 

[luvduvs]

well the first thing to check when you get to the car has the car been running before you got there if so walk away as this would indicate a starting problem.

That's really good advice

test drive the car for atlest an hour

I doubt most (private) sellers would let you test drive it that long...

 

[Steven]

It's not good advice, it's common sense. As for test driving for an hour, come again? I've bought and sold more than 20 FIRE engined Fiats over the last couple of years and never have I or would I put a seller through an hour long test drive, that's ridiculous. The advice offered here is dubious at best, daft at worst.

 

[luvduvs]

Well I think its good advice for people who are not familiar enough with cars - sure it might be 'Duh!' to some but it'll be 'Oh yeh that makes sense' to others. Its a bit like saying its common sense to turn the DEP off to allow certain programs to run; is this common sense to everyone??

The guy made an effort to give someone in need of help his thoughts and advice - give him credit where its due

 

[alexGS]

Steve - with over 13,000 posts, perhaps you can write us a guide on head gasket problems?

OK, well meanwhile I reckon that a head-gasket problem is infinitely-preferable to bodywork corrosion

With the Uno you need to be vigilant for rust at the edges of the floor, and at the top of the sill under the door rubber, around the rear struts (look in the wheelarch for flaking of the sprayed-undercoating (which should be body colour) - if it seems to be loose, suspect the worst. Removing the carpet or trim inside the boot may not be something you can do easily, but it may be worth arranging for this if the wheelarch inspection is less-than-rosy. Or actually, it may not be worth it... such cars are generally rusting apart in other places and the rust you can't see is always a lot worse than the rust that you can see.

Rust in the bottoms of the doors, or in places like the spare-wheel-well, is pretty common and probably not that much of an issue for what you want the car for.

Now back to the headgasket tests...
The cold-starting advice of Stephan1 is a good one, since in most cases the engine won't start very nicely if there is water in one of the cylinders. Check also, before you start, that the coolant is up to the correct level (should be a few centimetres below the top of the filler neck).

And I also agree with letting the engine warm up fully to the usual temperature of 90 degrees (middle of the gauge) - with an old/faulty thermostat, this may take a very long time and you might have to settle for 70. The fan cuts in at around 95 degrees (these are all degrees C, our Unos have gauges in C, I hope yours do too! ). I agree with luvduv's advice about checking for bubbles, but I think that without removing the radiator cap you can't really see on an Uno, because the radiator cap is the only fill-point. So, to remove the cap without scalding yourself, use an old towel folded several times and placed over the cap, and open VERY slowly. There should be a HISSSS but only a minimum of water should come out and there should not be a continued bubbling. If the level was a little high to start with, the level may gently overflow. If it seems to be spraying water everywhere with the temperature gauge reading below 100-degrees, then that is a concern. (Basically, a blown head gasket often pressurises the cooling system with combustion gases).

Obviously you can also re-check the level, which should have risen slightly(if anything). If it's empty, that speaks for itself too. Check for puddles under the car; perhaps there is simply a leaky hose connection or water pump.

If the temperature gauge is over 100-degrees, then it isn't a good idea to remove the cap, since the water will boil violently when you remove the pressure from the system. (The standard pressure of about 14psi (1 bar) raises the boiling point to at least 120 degrees. This is why the water will not boil until you remove the cap, with dangerous consequences).

It's hard to place much credence in exhaust-steam as a symptom, since in the winter/autumn/spring in the UK, you'd expect some condensation (white 'smoke') to be emitted most of the time. So instead, check the condition of the coolant (clean and green, plain water suggests it's been topped up often - why?) but the number one would have to be the engine oil on the dipstick and in the filler cap. Engines used in town can sometimes have 'mayonnaise' on the filler cap even when otherwise in good condition, but the oil on the dipstick should definitely show no signs of water contamination (formation of an opaque brown 'cream'), although the oil itself may range from gold to black.

If the Uno passes all these tests, then it's unlikely to have a head gasket problem.

 

[Steven]

Read Stephan's post on this thread in conjunction with his other posts and you'll catch my drift.