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Emmett, Lucas, and I are about at wits end trying to solve an overheating problem in my CRX. The car is an 89 Honda CRX with a JDM B16a engine (very similar to the 1.6L DOHC VTEC engine in the Del Sol).

Without a thermostat in the car it runs very cold. Last September while autocrossing the car the temp gauge would rise about 1/3 of the way up. On the highway maybe 20%. Driving the car around this winter, like stated above, it ran really cold.

With a thermostat in the car it will come up to temperature as it should. We can let it idle forever and it never overheats. We can also rev the car up and no temperature changes. However when we drive the car the temperature goes up to the point of overheating. If we stop the car and just let it idle the temperature falls back down. Exactly backwards of what you would think should happen.

At first we were using an Advanced Auto thermostat but later replaced it with an OEM Honda thermostat only to get the same result. We are thinking at this time that possibly the radiator is bad. We removed it and took it to a shop near where we work. They flow tested the radiator and it checked out fine.

We now start thinking it could be a bad head gasket and decided to go ahead and take the car into the shop. Like the radiator the head checked out fine. So we went ahead and had the shop further investigate. Unfortunately like us they came up empty. The coolant is flowing well and the radiator is warm all across with no cold spots that would indicate blockage.

The only thing that hasn’t been checked is the water pump. I have no idea if it is an OEM Honda pump or some bogus brand. In either case it is pumping fine so I don’t believe it is the problem.

The only other far-fetched thing we could think of is a timing issue at high rpms (advanced to far perhaps?) The shop agreed that this could potentially be the problem and recommended that we take the car to someone who is more specialized in Hondas.

A few other notes:

1. The heater core is disconnected and bypassed. Eliminate it as a source of the problem.

2. There appear to be no leaks in the system.

3. The fan comes on and operates as it should.

4. While our ability to bleed all of the air from the system may be suspect, even though I am certain we did, I trust the shop bled the system correctly. Let’s ignore this as a source of the problem.

As you can see I feel like we have pretty much exhausted every possibility except perhaps the timing. I was hoping someone on here may either have an idea or can recommend someone to us that can diagnose the problem.

TIA,


Chris

P.S. Michael don't you and Stephen have a Honda guy? The guy that swapped your JDM H22 into the Prelude. Do you think this is something he may be able to look into?

Gary Gordon
919-244-1042

He should be able to help you out. Tell him we sent you.

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Stephen Westerfield
2009 Infiniti M35 | 2007 Honda Fit Sport | 2005 Ford Mustang GT |2000 GMC Sierra |1992 Acura Integra LS | Super Westerfield Bros Acura Integra

Sounds like you tried everything I would have. If I had to guess, I would say that you still have air trapped in the system, but you say you don't feel that is the problem.

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

Thanks Stephen. I took down his info.

Richard I guess it could still be a possibility. I just assume that the radiator shop should have bled it correctly. When we bled the system we followed Ryan's method. We jacked the front of the car up as high as we could get it and let the car idle with the radiator cap off for about a hour. Quite a bit of air came out while we did this. When we finished we let it down, put the cap back on, and opened the bleeder screw. All that came out was water. So I am assuming we should have got all the air out.

I've never had luck getting all of the air out with it at idle. If you rev the engine higher, it allows the water pump to work a little harder and help get the air out.

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In need of car.

Have you taken the water pump out and inspected it? On my D series it was 15 mins to get it out, I would check it out they are very simple (and very cheap)

I know we have talked and I told you it wasnt a headgasket I still think there is air SOMEWHERE in the system. Try Jason's idea of driving around without the radiator cap on.

Try this, get one of those Infrared heat guns and take it out for a run, when it starts to overheat, pull over and shoot the various parts of the cooling system and find the hot spot, that's probably where the problem lies.

Welcome to the care and feeding of a 20 year old car.

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02 Focus SVT
STF 9

Sorry I should have mentioned the car was revved up quite a few times during the process.

I haven't tried Ryan's method, but it sound like a good one. I had problems with my Civic after I replaced the timing belt and water pump in that I thought it was bled, but it would run cool when parked, but if I drove it, it would skyrocket. If I came to a stop and let it idle, it would cool down. But it also never turned on the cooling fan either (which you said yours did and that is a good sign). In addition to Ryan's method, I would try to periodically squeeze the hoses to try to burp it.

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

Here's another Honda CRX owner that had an "air" problem. I'd suggest a new water pump (Honda OEM only), then rebleed the system. It took me several days / tries on the bleeder, even after running with the cap off to get the air out.

Also a good idea to replace the timing belt while you're at it, if you don't know when it was last done.

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Dustin Fredrickson
-- I'm a nobody --

Install a Prestone "T" in the line running into the firewall and uncap that and add more coolant into the reservoir. That'll be another high point for air to escape.

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Has no responsibility whatsoever.

I'm still thinking radiator. I tested the one I took out of the Del Sol (car that replaced the crx, Chris bought it from me) and it still seemed to flow fine, yet, all of my overheating issues disappeared when I replaced it (although the replacement was used). I had those same problems with the old motor that I put in before the B16. A new radiator fixed it. Unfortunately, like I told you last time we talked, it was out for quite a while and I made the mistake of not capping it and cleaning it out. I'm betting it got gunked up just enough to restrict the flow when it needs it. I'll check with my buddy and see if he has any 90-93 Integra radiators for cheap. I'll vouch for the air being extremely hard to get out of CRXs but the b16 was the easiest motor I had getting air bubbles out. Granted, I only filled the radiator once or twice with it but....

-Wes, if I'm not mistaken, he told me he bypassed the heater core so there isn't a line to the firewall.

-Dustin- Water pump is a bit more difficult to remove on the b16 when in the crx chassis. I also checked with my friend that I got the motor from and the pump/timing belt were replaced about 500 miles before I got it. Can't remember how many miles I put on it before Chris got it but shouldn't be anything close to needing to be replaced.

Chris, also the timing shouldn't be the issue. If the timing were out enough to make it overheat, it should be noticeable elsewhere as well. I don't know if you're keeping track but I remember getting something like 35+ with crap city driving and high 40s on the highway. It would also be noticeable by the exhaust as you would probably notice the pipe being red-hot (found that one out with the dual-cam d16 that I had in it before). Anyway, the new job has me slammed so I'm not online much but feel free to give me a call to discuss any other ideas or problems. 610-1049

Its plausible but I know where Chris is at, he has thrown money at the problem and not fixed it before.

I got a new radiator from NAPA for a little over $100, it was all metal too.

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02 Focus SVT
STF 9

Problem's solved.

It's none of the above. When Dave did the engine swap he bypassed the heater core (who needs heat in a race car right?). Well he did this the wrong way such that when the thermostat was closed water didn't circulate around the engine at all. By the time the termostat opened it couldn't make up for the hot spots.

I'm not quite sure how we didn't manage to blow the head gasket. We have had it checked out and all's well.

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Emmett

Chevrolet Cobalt SS