Disappearing coolant, cracked block?

[AZmike]

The A20 in my Prelude (same as 86-87 LXi) has always gone through coolant quickly (about 1 quart/175 miles). Since the exhaust made a huge cloud of smoke when I had rust remover in the cooling system I assumed I had a head gasket problem and replaced the head gasket. That didn't seem to do it since it still produced a fair amount of smoke up to several minutes after starting (especially after sitting a few hours). So I got another cylinder head, had it rebuilt and swapped it in. The engine smokes less now (so I've been using the car), but it still consumes coolant at the rate mentioned above. I'm guessing that the block is cracked since when I bought the car it had an overheating problem due to a clogged radiator (that was full of the copper stuff that 'stops leaks') and I've swapped the cylinder head and the radiator was pressure tested before I installed it. I recently found that the bearing on the water pump has some play in it, but I don't see any leaks around it while it's running.

So does it sound like the block is cracked and I should swap engines? Is there anything else that I could try to stop this otherwise perfectly running A20 from using coolant? Thanks for any suggestions.

[shepherd79]

hmmm, i am sure you have a leak somewhere. i mean external leak.
i don't think the block is cracked because if it was your would see coolant in the oil or your car would smoke every time even when it is warmed up.
i think you should look around and try to find a leak somewhere outside. like hoses and stuff like that.

[AZmike]

Isn't is posible that the crack only extends between the water jacket and the combustion chamber? What else would expalin the huge increase is smoke after I had let the car sit for a few hours after runing the car with the rust remover in the cooling system?

[dXsquared]

maybe its an intake gasket.. sometimes they leak and let coolant in the intake passages... no coolant in the oil, but it will lose coolant and overheat from time to time

Travis

[Bioforge]

I would check the hoses around your intake, its possible that it is leaking in their, and by the time that the engine warms and opens the line, it leaks in....is there any loss in performance?

[cruznz]

coolant pressure tester would find a leak if you can buy/borrow 1

Colour of the smoke? White I assume?

[AZmike]

I'll take a look at the throttle body. That's the only place coolant runs through the intake other than a tube straight through between the runners. Is there a specifc gasket that you suspect Travis?

Aside from the missing fluid, the performance is fine. I had checked over most of the intake coolant hoses when I replaced the cylinder head, but there are so many connections going over everything once more won't hurt.

Any other ideas?

[AZmike]

coolant pressure tester would find a leak if you can buy/borrow 1

Colour of the smoke? White I assume?

The smoke was gray. It seemed more like white (coolant) than blue (oil). If the coolant is leaking through a small crack in the block, how would the pressure tester find the leak? Would I just look for extra smoke on startup?

[cruznz]

external leaks with the tester.......there's also another tester called Tee-kay Head checker....dont know if it's over where you are,...but it detects exhaust emissions in the coolant and is easy and quick to use.....but going by the colour of the smoke you definitely got an internal leak somewhere,...have you done a compression test?

[zero.counter]

You have either a warped/cracked head, because if there are no obvious signs of external coolant leakage, it is burning off into the cylinders and will eventually lead to a massive engine failure. If you can take the head off again, check the mating surface for abnormalities with a ruler or have the block checked thoroughly by a machine shop. If it is slightly warped, it may just need a little resurfacing (affecting compression). If it is deemed not worthy, check out a junkyard for another engine.

Check the plugs for weird fouling any unusual debris on the end (possible water burning).

I have seen where the rust remover does such a good job that it flushes out the rust and any particles that were blocking internal leaks and then all kind of problems arose.
I have also seen where the thermostat sticks and either does not allow fresh pump water through or lets its through constantly, making the water pump work till it fails quickly.

[AZmike]

The head (pulled of a junkyard car that threw a rod) was pressure tested before the valve job and then machined flat. One of the valves was bent a little and was replaced. The plugs that had been in the engine before the rebuild looked perfect--gray-tan with square eletrodes. They have since been replaced. I haven't done a compression check--I haven't invested in that tool yet. There was a noticeable increase in torque required to tun the engine over by hand after the valve job though.

I'm still not certain that it's an internal leak since I only saw smoke the first few days after the reassembly. Once the engine is at operating temperature the coolant could escape as vapor, right? I spent enough time trying to fix an idle problem after that I'm sure I would have noticed if it was a liquid leak. I did clean the EGR passages and intake manifold with carb cleaner and knocked a lot of filth loose. That might explain the little smoke after startup each time before I had driven more than 100 miles. I'll pull the plugs tomorrow and see if the new ones look ok. They'll have about 450 miles on them. Is that long enough to develop the deposits?

Thanks again for the suggestions so far. Any other things I should check?

[cruznz]

hmmm.....well....I would still suggest a coolant pressure test,you say there was no sign of leaks at the water pump when running and there was play in the bearing,...have you checked the pump after its at operating temp. and engine turned off,...(this is where the tester is handy, so as not to get burned),...or any sign of rust below the pump?

I have come across cracked valve stem guides which have caused over-heating problems but not in a Honda yet just in Fords...lol

[danronian]

Also if the coolant is exposed to combustion, it generally loses all anti-freezing ability (even if the coolant is still green). So you could check the freezing point of the coolant. I had a similar problem (not with the accord) and it was caused by a minute crack in the head. But since you replaced the head and it still loses coolant but not as much I would suspect a warped block.

[badmanferg]

i had a similar problem this week, i was burning the antifreeze, similar to your circumstances....i had a leak in my heater hose, small as hell, but it was definitely enough to kill a quart in no time...i suggest checking there before thinking about cracked blocks, sometimes its the little things...peace


-kevin

[Mike's89AccordLX]

Get your coolant system pressure tested. I did this today in school and found a headgasket leak and I have been tearing the motor apart and will have it done tomorrow.

[AZmike]

I double checked all the hose fittings and some of them were not as tight as they could have been (not loose though). Now the consumption (or leak) rate is much lower. I've probably used less than a cup of coolant during the last 300 miles. Now the smoke at startup after sitting a while is looking more blue than gray so I'll be heading over to the place that rebuilt my cylinder head with a few questions. Thanks for the suggestions everyone. I'm glad I didn't tear the engine down for the thrid time.