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Hi folks, I'm new to the forum. Not seeing any posts for cars as old as mine, so here's a new thread:

I have a 1980 Civic Wagon. I got my engine rebuilt a few years back and it's been running great. Except I keep losing coolant somewhere. I don't think it has been going into the oil. I don't see any leaks or puddles on the floor. Just seems to disappear.

I was doing some errands the other day, and the engine seemed to get weaker, and I saw that it was very hot. I pulled over and let the engine cool, and eventually made my way home. As the engine got cooler, it seemed to start and run fine.

I let it sit overnight, and the next day I checked the coolant. Couldn't find any. Also checked the oil. It has a gray frothy look to it. So now there definitely is coolant in the oil.

I also noticed a clear liquid dripping onto the carburetor from the air cleaner. Although the interior of the air cleaner was dry. Not gasoline, so it must be coolant. I've never seen that before. Maybe condensation from the valve cover vent?

Anyway, I fear I have a bad head gasket or cracked block or something. Not sure what to do next. I think I might replace the oil and coolant and see if mixing still happens. Is it possible that coolant in the oil could be due to the engine overheating, or is it definitely indicating something critical is broken?

No way I can afford another engine rebuild. My financial status since then has tanked.

Suggestions and advice welcome.

 
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Start with a block test. Free tool rental at parts store and $10 for test fluid to confirm. Based on symptoms sounds leak a head gasket breach. If it's a crack in the block you'll need another engine, if it's a crack in the head you will need another head. Most likely the head gasket is the issue and a warped cylinder head from overheating. If the head doesn't have a crack it will most likely need to be milled down by a machine shop to get it back into spec.

 
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Ok. I picked up a block tester and dye today. Not sure what to do about the head bolts though. My understanding is that they're torque to yield, and not available anymore.

 
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I have some pictures to share from when I first got my car home.

I think the liquid above is coolant condensation from the rocker arm cover vent? It's definitely not gasoline.





I hooked up the block tester, and was able to get the dye to change color, but it took something like 15-20 minutes.


Anyone know of a way to differentiate a crack from a bad gasket? I've heard the cracks can be hard to see, and my eyesight is not so great.

 
Rep Power: 211

If that's the oil cap in the second pic you posted it looks like it has milk-shake sludge on it when coolant mixes with oil from a breached head gasket.

As far as gasket vs crack it doesn't matter at this point because the head has to be removed either way. Most likely is the head gasket, though.

Cracks in D-series engine blocks are very uncommon. However, the most likely spot would be between, on or near cylinder walls.
Inspect head for crack as well or better yet bring it to a machine shop for: inspection for cracks, planing (resurfacing to flat specs.), valves leak testing. Also, a good time to install new valve stem seals.

 
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I've ordered a leak-down tester. If I can figure out which cylinder, if any, are leaking, then I'll know better where to look for any cracks that might be there. Also, it would be nice to get a before and after reading. I've often wanted one of these testers for the motorcycles I tinker with anyway, so it's about time I got one.

So my plan currently, is to change the oil, and do some compression and leak-down tests. I also plan to back-flush and bypass the heater core. As far as I know, it's never been back-flushed before. It works ok, but maybe I can get a better heater out of all of this.

From there, I'm not sure. I'm considering removing the thermostat and putting in one of those stop-leak products. I've read a lot of reviews, and watched a lot of videos on the subject. These products seem to be very hit-and-miss. Seems to me it depends greatly on the nature of the leak, and the condition of the cooling system. And to a smaller extent, the user's ability to follow directions. I'd give it a 50/50 chance of working. And if it works, a 50/50 chance of actually staying fixed for a long time. I don't expect a miracle cure, but given how slow the leak seems to be, I think I'll give it a shot.

 
Rep Power: 211

Great approach: Leakdown and compression test. If compression is low in two adjacent cylinders then there is a tear/breach of the head gasket between those two cylinders. If, one cylinder or two non-adjacent cylinders has low compression it points to either broke/stuck compression rings or leaky valves. Please read the related articles linked in my signature.

Bad approach: Don't use stop leak product(s). Yes, it could possibly work for specific type of head gasket breach but there are several types of breaches as shown in one of my signature links: http://www.agcoauto.com/content/news/p2_articleid/200 . At best even if it does work it will most likely fail within a few months.

Also,there is potential of doing more harm than good as that stuff can possibly clog the radiator, heater core and thermostat. If so, those parts will need to be replaced.

Heater core: If you flush it do not use more psi than is specified on the radiator cap/system is designed for. A blown head gasket can also affect heater core function and cabin heat. If exhaust gases are entering the coolant system via a breached head gasket then it will most likely produce bubbles that will cause air-locks in the heater core.

 
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any updates?

 
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Still gathering tools and such. I should be able to pick up the leak-down tester on Monday. I've got all the stuff I need to change the oil.

It looks like when I drain the radiator, up to 0.9 gallon will come out. Probably less as it's really low right now. The coolant in the engine is only 3 years old. That's when the engine was rebuilt. Not sure about the radiator though. I'm sure that would have been flushed and refiled, but I can't remember if it was replaced, or if it was my old truck that the radiator was replaced.

Just thoughts rattling around in my head. Maybe it doesn't matter. I probably won't be getting to it until late next week. My sister's alternator ate itself, and I'm the closest thing to being a mechanic that she can afford. At least I know my way around alternators. Her car will be up and running way before mine will, LOL.

 
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I just realized that I don't know how to find TDC on the other three cylinders. Just the 1st one. Can't do the screwdriver in the sparkplug hole, because that's only the prefire chamber, not the cylinder. Any suggestions?

 
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Ok, I think the valve adjust section of my shop manual will help me find TDC on all the cylinders. I got the oil and filter changed today, and pulled out the sparkplugs.

Not sure if it shows on the picture, but there looks to be a bit of powdering on the electrodes. Might mean some coolant contamination, I think.

 
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I got to do my compression tests today. The range was from 130-147 PSI. I was hoping for anything above 90, so I'm pretty happy with that.

Also, I got into the rocker arm area. Pulled the air cleaner, A/C compressor, and the valve cover in order to get the timing cover off.


I've never used a leak-down tester before, so it took me quite a while to figure it out. Finally, I got a reading on cylinder 1, which read 10% loss. But then night time happened and I'll have to do the rest of the cylinders later.

Part of my problem was lack of air pressure. The instructions said 45-100 PSI, so I set it about 50, and got 0% or less. I knew that wasn't right, so I watched a few videos like Eric The Car Guy, and they were all using 100 PSI. So I bumped mine up to 90, and got a real reading. Another issue I haven't solved yet is that the pressure wants to make the engine turn over, losing my TDC position. Still working on that one.

 
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Use a breaker bar on the crank to keep the engine in position, or leave it in gear

 
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Thanks! I will try those.

 
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Got some results today. The compression of cylinders 1-4 were 145, 147, 140, and 130 PSI.
Also finished the leak down tests. Results of those were 10%, -2%, -5%, and -3%. I must be using this thing wrong, but I can't see how.
An interesting observation though is that during the leak down test, I could hear air escaping into the cooling system from cylinders 3 and 4. So there is definitely an issue. Unfortunately, I can't seem to rule anything out. Next I plan to check the torque on the head bolts. But they are a bit weird. The outer 4 need T-55 bits, and the inner 6 need 10mm 12-point star sockets. I have the bits, but I'll have to go find the socket.

 
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Here's a video of the progress I've made so far:

I wonder if my little compressor doesn't have the CFM to keep up with the tool? Maybe the tool is actually defective.
Anyway, my 12 point torx sockets came in, so time to check the head bolts.

 
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A little more progress:


The short version is:
- I fixed the leak on the leak-down tester, and now it actually works.
- I re-torqued the head bolts. At 22 ft-lbs, one or two bolts actually moved. All the rest but two moved at 43 ft-lbs.
- After re-torquing, I did another leak-down test and got real numbers this time: 10%, 10%, 8%, and 9% from cylinders 4-1 respectively.
- Also after re-torquing, the leaks into the radiator are gone. I don't know how to interpret that.

Don't know how to proceed now. If the leaks are gone, then... what next?