My 1980 Civic overheated the other day, and much of the coolant is gone. First thing I saw when I opened the hood was water dripping all over the carburetor. Condensation from the rocker arm cover maybe?

I checked the oil, and it looks like the missing coolant went there:

Here's what the oil fill cap and cover opening look like:


I rented a "block tester" and dye to see how it would react. It took 20 minutes, but the dye finally started turning from blue, like what's in the bottle, to... whatever that color is in the picture:


I'm not sure what all this means, exactly, but I think I'm going to have to remove the head and at least replace the gasket.

What to you all think? Is there a way to differentiate a bad head gasket from a crack somewhere? Before I start disassembling? I've been searching, but haven't found much.

 

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.

 

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?

 

Ok, I think the valve adjustment section of the shop manual will show me how to find TDC. In the meantime, I got the oil and filter changed, and pulled out the sparkplugs.

Not sure if it shows in the picture, but they do seem to have a small amount of powdering on the electrodes. Suggests some coolant contamination, I think.

 

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.

 

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.

 

Here's a link to a video I put together on my efforts so far:

 

A bit late, seems like you found your issue when you heard the bubbling when doing cylinder 3 and 4...
Glad that you found out that the throttle need to be fully opened when doing the compression test, the values will be higher... and of course it is usually done on an engine at operating temperature...
Good move on changing the oil, coolant is a bit toxic on crank bearings, it has a tendency to etch the metal of the bearings...
I do not know how to differenciate headgasket from cracked block or head...
Head bolts do not loosen up, because of the high torque value, on the latter years it is recommended to change the head bolts because they stretch when torqued...
Also not too sure on your vintage, but the 3rd gen has a carb to intake gasket that is hard to find...

a good article https://www.hotrod.com/articles/cyli...akdown-tester/

 

Thanks for the reply!

Yeah, I'm holding out little hope that checking the torque on the head bolts will yield anything. I saw one guy with a head bolt that stripped out the threads. Unfortunately, head bolts for this engine are not available anymore, so my options are limited. Most folks with this engine reuse the old ones simply for lack of an alternative.

Anyway, I've never done a compression test on a warm engine. I'm no mechanic, but I fiddle with motorcycle engines and other small engines. Mostly non-running ones. The idea with those is that when cold, they need a minimum compression to be able to get started. Generally 90 psi. Then it's assumed the compression will go up a little as the engine gets warm. But yeah, I'm supposed to have the throttle open. I'll re-test with the throttle open after I check the head bolts. But I'm 99% sure the head is going to come off anyway. I'm just procrastinating at this point.

I'm kind of thinking that my leak-down tester has a fault. It does make a hissing noise when I bring it up to pressure. I may replace the connector and see if that helps. That's the only thing I can think of. If it's already leaking when I zero the gauge, and then seals once connected to the cylinder hose, then maybe it is actually experiencing less leakage when connected up? But with an obvious leak between 3 and 4, and the radiator, I suppose the leak-down tester's readings don't really matter at this point.

The good news though is that I have already located sources for all the gaskets I should need. Head gasket, (obviously) intake/exhaust gasket, and the ones that go with the weird heat shield thing between the carburetor and intake manifold. There's probably more, as lots of stuff needs to be pulled out of the way, but I'll figure that out as I go.

 

you may need to make sure that the head is plane, on these aluminum engines the pieces can warp due to heat, not too sure about cracking. When one of my kids neglected to add coolant because of a radiator leak, I took a drive with a new radiator... after reinstallation, I checked the oil level... and it was way above the max, so I knew there was a big crack somewhere, the oil and coolant mixed really nicely... I sold the jeep letting the buyer know that it was not running with a leaky headgasket or worse, and he should do an engine swap as the current engine had close to 200K... indeed it was worse, when I checked a few weeks later because I was tempted to do an engine swap myself.... not only the head was cracked, but the block as well, which the shop that did the headgasket did not bother to check... the buyer drove the 10 miles to Mexico , stopping every 5 min before running out of water or oil, and the locals did the work.

No need to redo your compression with the opened throttle, the numbers are good enough, and you have found the culprit with the hissing sounds

Yes motorcycles are easier, lift the engine put it on the bench ....

Good luck

post edit: did you see the comment about the swap and the headgasket comment

Quote:
Originally Posted by Derreck Warfel View Post
If the EM engine is available I maybe interested in it. I have an 83 hatchback that already swapped it to a 1.5 from the 1.3 but keep blowing head gaskets. That last time it went it popped pretty good so the engine/parts could come in handy.
Usually, replacing the head bolts with grade 8 equivalent studs cures the head gasket malady...

 

Hm, grade 8 studs. I'll look into that, thanks. Especially if it's something that helps prevent future head gasket issues.

 

Well, class 8.8 studs are really hard to find. I'm looking for M10-1.25. Most of what I could find was M10-1.5. I did find some threaded rod, but it was horribly expensive. I did make some progress on the engine:

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?

 

this is progress... I read somewhere, that torquing depends on the type of lubricant used on the headbolts... some need retorquing after a few warm up cycle and some miles... as there is no way to find out how the head was done previously... seems like a good achievement... time to go for a test drive

Yes they are expensive and as stated in the check list at the ARP site, it seems that some stretching is to be done on new bolts... really -stretching- In my rebuilts I have lucky and reused most of the headbolts... the engine is still running strong...