Head Gasket?

I'm suspecting I have a blown Head Gasket, but a compression check shows 125psi cranking pressure on all 4 cylinders. (That's about all you can expect from 8.5:1 compression ratio.) I am wondering if there's another possible cause of the symptoms.

When I last drove the car, it ran fine. I've never had overheating issues with the car, this time included. I stopped in the driveway to open the overhead door, then drove in. When I got back out of the car, there was a trail of coolant from where I stopped into the garage. The plastic coolant tank had ruptured. Now, the engine will start (with difficulty) & run (gets better as it runs), but won't rev freely. RPM will rise to a point, but feels labored. Coolant flow is visible in the tank. When RPM climbs, bubbles (lots) appear in the coolant.

I've purchased a replacement coolant tank, radiator cap & what I think I'll need to replace the head gasket (gasket set, timing belt + tensioner bearing).

Anything I should be looking for, before going ahead with disassembly?

Thanks,

Brian

If you end up replacing the head gasket, while the head is off, take it to a local machine shop and have it checked for flatness to spec. If it is not within spec, it should be resurfaced by the machine shop.

Since your "bubbling" could also indicate a breach of the cooling jacket in either the head, block or both, while the head is at the machine shop, have them look for any defects in the casting (crack check, pressure check).

The above is not specific to FIATs or X1/9s, it is a standard "best practice" across ALL makes, models, and years.

Check the oil

Every head gasket I ever replaced was revealed by foamy white muck on the dipstick. Water and oil do not mix well and you will see right off something is wrong. My '79 stock engine read 145psi for #1 and 150psi for #s 2,3+4. You have any blue smoke from exhaust? I do not think bubbles should ever be normal in the expansion tank... Not much back story for us to go on like mileage, prior faults, or repairs effected. If you have repaired a blown head gasket did you have the head checked for warp? If you are set on valve clearances you can carefully remove cam, tower and tappets have head checked for cracks, warp and I guess a leak test then reassemble everything with the tappets matched to their original valves and avoid a complete set up. Did this on an '83 low milage and everything worked fine. Do check clearances just to be safe but as long as you put things back the way they came apart you should be fine.
Good luck

The same pressure in all four cylinders would indicate no headgasket breach between cylinders. Did you check for oil in the coolant or coolant in the oil (chocolate milk on the dipstick). I'm not saying you didn't blow a headgasket but evidence you gave does not necessarily indicate such.

I'd be reluctant to start a head-removal exercise on the evidence so far - with Carl, I'm not saying that you don't have a head gasket problem, just that it's not yet proven.

Bubbles in the tank are likely just the air in the tank being mixed with the churning water... They might be a sign of a breach between cylinder and water jacket (head gasket, cracked head, cracked block) but that's by no means certain, and you want to be certain before you commit to major surgery. You can pump compressed air into each cylinder (at TDC valves closed) using a leakdown tester, or there are chemical kits that will find exhaust gases in the coolant. A coolant system pressure tester will also find such a breach (but also probably a bunch of small coolant leaks you didn't know you had).

Do the plugs show evidence of water in the cylinders? How does the oil look? Unless they suggest a problem, I'd be checking valve timing, ignition timing, fuel delivery next.

Do a leak down test (pressurize cylinders with air and see if/where the leaks come from).
You'll probably get bubbles in the coolant tank??

More details:

I should have mentioned the oil: The oil on the dipstick looks normal. It does not look like an oil/water emulsion. The exhaust didn't look smoky, but some water dripped from the tailpipe. (Condensation or Coolant? I don't know.) The spark plugs didn't look unusual.

I should also have given some background: The car's an '81, fuel injected, with about 65000 currently on the odometer. It had been non-functioning for a long time when we purchased it. Engine was seized. My father & I disassembled/reassembled the engine, repairing whatever we found along the way. We had a valve job done at a local shop, and the head was skimmed at that time, to ensure a flat mating surface, but didn't mill it to intentionally raise compression. The block checked out good. That work was about 5,000 trouble-free miles ago.

Yes, I'm reluctant to tear into a head gasket replacement with some of the normal checks pointing away from that. That's why I posted the question. But the bubbles in the coolant when trying to rev the engine seems like a pretty strong indicator. A cracked block or cracked head could have me wishing for a blown head gasket.:sad: I'll try to do a leak-down test next week, and report back.

Thanks for all the input, so far.

Brian

"Bubbles in the coolant" can mean a lot, can you post a vid or pix?

Some amount of little tiny bubbles are to be expected when any liquid is being pumped thru a system. Pot of water boiling sized bubbles---that's another thing altogether.

You can buy a test kit that checks for combustion byproducts in the coolant.

Lots of bubbles

I'm not up to speed on making/posting video. Sorry.

I just started it up, for fresh observation:

The water from the tailpipe that I saw in the brief time I ran it seems like more than I would expect from condensation.

At idle, I see no bubbles in the coolant tank. At 3000 RPM the bubbles look like a pot coming to a boil. Not like bubbles from pouring a Coke. It's hesitant to climb to 3000, and nearly refuses to go higher.

I searched Advance Auto Parts website for "coolant test" and 2 kits of test strips came up. They reportedly read boil point, freeze point, & pH. I've got pH paper on hand, so I just tested it. Looks like 8-9. If there's a correlation between pH & presence of exhaust gas, that would be a worthwhile piece of info. If the test strips you mention are testing something else to determine the presence of combustion by-products, I'd appreciate more information about them.


Thanks again for any/all input.

Brian

coolant leak

I have had a problem with the plastic tanks too. some had minuscule cracks along the bottom ,to the center where the two halves are fused together, separating causing them to look like a full moon at night. if the tank has a leak, then air has most likely entered the system
1 check the thermostat and make it is performing as it should and while you are there check the housing to head gasket. best to replace while your there anyway. you might find that the po might have used the wrong gasket.
2 nose up as much as possible and fill the tank with the drain valve on the radiator open (heater valve open too) and fill the tank till you have a good flow of water out the drain.
3 when you have no air coming out, then add the coolant to the tank.
the CR reading across the board is a good sign.
keep us posted!!!
mikemo

For example:

http://www.amazon.com/Lisle-75500-C...4&sr=8-1&keywords=head+gasket+chemical+tester

Tester

Thanks, Dan. That's interesting. I may try that...

check the head bolt tork

When you had the head off, on reassembly, did you use a metal head gasket? After assembly and run for awhile they must be torked again or they can fail. If you used a "blue" head gasket they do not require additional re-tork. I learned the hard way as always.

Mine is also an '81
also had sat
had 67,000 miles
mine was NOT siezed
had valve job done, did skim the head
it did puked a head gasket about 5,000 in too,
bit eery, no?
Mine went between cylinders so was just compression loss, took me four tries to get good again.
Not a huge deal if it is a HG, it's been apart recently and you know how to do it. So for you, a weekend job probably? I would want to be sure that's what it was too though.
I'm told you can gut a spark plug and make an air fitting out of it for a compressor and have your own leak down tester.

Steve Sellers said:

When you had the head off, on reassembly, did you use a metal head gasket? After assembly and run for awhile they must be torked again or they can fail. If you used a "blue" head gasket they do not require additional re-tork. I learned the hard way as always.

Click to expand...

MLS (metal layered) gaskets would not be the reason for a re-torque - the style of head bolt (TTY or standard) would dictate that.

The leak down test will tell you where the pressure is escaping - you will know empirically whether it is to the crankcase, the cooling system, or out past the valves. Then you can determine the next step...

My recent blown head gasket / piston issue had NO coolant or oil mix.

you can see the deformation of the fire rings, allowing pressure to escape into the crankcase AND coolant passages.... I had excessive bubbles in the tank when revving. If the tank ruptured seems likely you have a pressure leak into the cooling system...

Head bolts

This sounds all too familiar. I had the exact same symptoms at the exact same milage after doing the exact same thing on my 85 . Gasket was leaking in between # 2 and # 3 . The compression is leaking from the cylinder into the coolant passage nearest the cylinders forcing exaust into the coolant. I made the mistake of reusing the tty head bolts . A new set of head bolts that need to be retorqued to the proper specs with the correct head gasket to go with from Matt at Midwest seems to have fixed the problem . I have been driving it every day since November and no problems. I would of course check every other posable thing before tearing of your head but this sounds exactly what happened to mine.

Leak Down Test

Thanks, everyone, for the thoughts shares so far.

The results of the leak-down test seem to confirm the compression check, and point away from the head gasket. The tester is calibrated for an engine with different cylinder volume, so the numbers may be skewed, but should have meaning relative to one-another. Top number is pressure held in cylinder. Bottom number is regulator pressure:

Cylinder #1: 90/99
Cylinder #2: 93/99
Cylinder #3: 97/100
Cylinder #4: 95/98

At this stage, I guess we'll just replace the coolant tank, re-fill the cooling system, and see where we are.

Brian

Edit: Leak-Down test results, expressed as %-loss: #1-9%, #2-6%, #3-3%, #4-3%.

compression readings

if the cylinders are within 15% of each other, I don't feel a head gasket leak is your problem. all you have to have is a stone or rock kicked up to put a small enough hole in a hose or pipe that you can't see. I would go and get a coolant pressure tester (borrowed preferred)
and pump it up a few pounds over the cap rating. pull the dipstick too.
if you hear a hiss of air or coolant dripping there's the leak. literally a pin hole.
remember that it is under pressure and the leak will most likely dissipate as steam and suck air back as it cools.
keep us posted!!
mikemo

Cylinder leak down is usually expressed as a %age loss...

It also is pretty definitive...air can only escape from so many places.

to check the head gasket integrity make sure the coolant reservoir is topped up brim full, then any air escaping into the cooling system past the head gasket will cause the level to rise and spillover... you won't necessarily get bubbles per se from a leakage test... as the air may get trapped at a high point in the motor, but it will displace fluid...and show as a small %age leakage loss.

SteveC