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Head gasket?

yugo4life

New member
Joined
Apr 29, 2009
Location
Peoria, IL
I just purchased a 1984 244 GL in October to serve as my DD. There was a known coolant leak when I bought it and the PO admitted that he had added stop leak to the system. I have daily driven it for about a month with no issues (except for the 1000's of known issues), but this week I have blown off the radiator overflow hose 3 times. When I first got it, I drained/flushed the coolant to get rid of the stop leak knowing I would just live with the leak until I could fix it. Since then, I have noticed an oily substance in the coolant, but I can't tell if it is residual stop leak or oil. I have checked the oil level every day and have not noticed water in it or the oil level drop. I will do a compression check tonight or see if my borescope can see anything. Could my radiator cap be bad? I have noticed it get hot, but only after the overflow hose has popped off and dumped my coolant.

I am pretty sure it is the head gasket, but I am hoping it is something else. This is my first 240 and I have not learned all their quirks yet.
 
You mean the small hose that runs to the coolant reservoir? What color is the pressure cap on the coolant reservoir? If it is blue or gray you need to change it to the black cap. The pressure is higher with the blue and grap cap and 240 series use the black version.

You can also do pressure test of the cooling system to see where any leaks are. How old is the thermostat? If that is slow to open because it's old that could cause too high a pressure in there.
If you do replace the thermostat make sure you install it with the toggle valve to the 12 oclock position. Stock is 87C.
 
You mean the small hose that runs to the coolant reservoir? What color is the pressure cap on the coolant reservoir? If it is blue or gray you need to change it to the black cap. The pressure is higher with the blue and grap cap and 240 series use the black version.

You can also do pressure test of the cooling system to see where any leaks are. How old is the thermostat? If that is slow to open because it's old that could cause too high a pressure in there.
If you do replace the thermostat make sure you install it with the toggle valve to the 12 oclock position. Stock is 87C.

Yes, the small hose to the coolant reservoir has blown off at the reservoir. The car has a black cap. I have a new thermostat ready to go in, so I may start there. I have a timing belt and water pump on order as well, since nothing looks new and I question the PO's maintenance schedule.

You can also do a "dye test" aka "block test" by renting a tool from AutoZone (test fluid is ~$10). This will detect combustion gases in the coolant reservoir = bad headgasket.
https://www.autozone.com/loan-a-tools/loaner-block-tester

Good thinking, I will try a compression test tonight and if that is inconclusive, I will stop by and grab this.
 
Another easier test to do is to take the cap off of the reservoir, start the car and watch for a trail of bubbles coming up through the fluid in the reservoir.

IMO this will only reveal if the hg is leaking at idle/no load...so it may be inconclusive if your coolant venting only occurs when driving.
 
So, I changed the thermostat last night and while it seemed intact and functional, I did not test it. It did have some gooey/fibrous junk wrapped around the internal shaft. I will post pictures when I get a chance. I checked compression and I am not quite sure what to think.

Method: Car was nearly cold, not ice cold, but cold. I had warmed it up but then had to run and do other stuff and was getting tight on time. Ambient temp was around 30 deg F. I removed all of the spark plugs and looked inside the cylinder with a flashlight and saw no coolant in any cylinder. The spark plugs were all white/tan/pink except cyl 3 which was black, not oil covered or excessively black, but you can tell it has more carbon build up than the others. I had the gas pedal pressed for all tests. The odometer shows 173k miles so I am a little shocked at how high the compression is, even in the lowest, especially since the engine was cold.

Cyl 1 - 190 psi
Cyl 2 - 185 psi
Cyl 3 - 170 psi
Cyl 4 - 205 psi

Obviously I suspect Cyl 3, but I would have thought it would be much lower. Maybe it only shows up under load or when it is warmer. I will probably drive it until Christmas and then use my time off to replace it anyway. Unless I find it is something else in the meantime. Anyone else suspect anything?
 
The "good news" I suppose is that changing out a HG on red blocks, esp. non-turbo ones is not really that difficult for a reasonably competent shade tree mechanic.

A bit of a hassle but not all that bad; certainly easier than replacing the heater core and fan unit.
 
The "good news" I suppose is that changing out a HG on red blocks, esp. non-turbo ones is not really that difficult for a reasonably competent shade tree mechanic.

A bit of a hassle but not all that bad; certainly easier than replacing the heater core and fan unit.

Yeah, I just replaced the heater core and fan last month and this looks like a piece of cake in comparison.

I replaced the thermostat and flushed the coolant (straight water at this point just to flush) and everything seems fine so far. I drove it around town and on the interstate over the weekend and had no issues overheating. The fluid level has stayed the same as well so far. I drained the water and filled 50/50 with water/coolant and I will just keep an eye on everything. While I don't mind changing the headgasket, I would prefer to do it in warmer weather as my tiny garage has no insulation and terrible windows.

I hope it either waits until summer to go (or better yet, never) or it goes in the next week so I can do it during my time off after Christmas.

Thanks for the help!!
 
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