GLAH!!! 1988 Honda Civic 1.5L DX, OVERHEATING...

[Donald Shimoda]

Howdy, Folks!

Okay - here's the skinny...

This ol' 4-banger purrs along like a dream. Missus Shimoda's car; she drives it right.

Anyway, the radiator had developed a pinhole leak about 2 months ago, on the top. No worries - it would work fine, run cool, but need fluid about every week or so.

Earlier this week - it crapped out H-O-T. Not redlined, but the Missus said it got to the "pretty toasty" just below the top white line mark.

Okay.

I realize it needs a repaired/replaced radiator, so I pull the old radiator today to prepare for whatever.

Sure enough - the "pinhole leak" is now a crack about 3 inches long. Plastic radiator(too weird; I'm very old school, so am only familiar with metal radiators), repairs look to be about 80-100 bucks, replacement for $139, so I replace.

STILL overheating.

- Overflow working; HOWEVER, it is not drawing fluid back into the radiator fom the overflow bottle when it cools down. Bad cap?

- No leaks - car runs great, don't think it's the head gasket.

- Hoses all carrying fluid to and from the block - don't think the thermostat is bad, will replace tomorrow JIC. Clogged holes in the block?

- *Maybe* a bad temperature gauge sending unit? Ususally when these things fail, they either read "hot" or "cold;" the car runs fine for a while, then creeps up to about halfway up the "tape," then shoots to almost redline PDQ. Have a spare temperature gauge sending unit, will test with it tomorrow.

- Hoses - internal collapse? They seem okay...

So...**what am I missing** before I get to:

BLOWN HEAD GASKET - unlikely, as the car is running well, no contamination in the oil, no white clouds spewing out of the tailpipe.

FAILED WATER PUMP - no bearing noise, if the fins were worn/wearing out, I doubt the overheating problem would have come on so suddenly.

What am I missing?

All constructive advice welcome.

Thanks!

 

[CTCStrela]

GAHhhh is right...damn honda 1.5's are notorious for this kind of thing...

First thing to do: BACKFLUSH the motor...teeny water passages...possibly clogged now.

Second...leave the cap off of the motor and jump up and down on the motor...these cooling systems are known to airlock (IE have bubbles in them).....have it running while you do this, and keep adding water... if you never see water *moving*, then either the thermostat is stuck almost shut, or the waterpump vanes are corroded away...

Make sure the thermostat is NOT sticking (just replace it). Get a new radiator cap also...

Cooling fans coming on? If not...there is your culprit...

I know this is going to sound really assinine..but your replacement radiator may simply not be good enough...some of the really cheap ones do not use aluminum cores, and have lousy heat transfer...

next...are you *sure* it's actually getting hot, not just a gauge malfunction (not to insult you, but just using the "shotgun" approach here...)

Let me know what's going on with it

by the way, how many miles are on it?

 

[Bigbng]

I'd would add to CTCstrela's comment about the rad cap and checking it, just because it's new, doesn't mean it can't be faulty.

You didn't by chance put any of the radiator stop leak stuff in did you?
If so, you water jackets could be plugs with that too!

Is it possible the heater core for heating the interior of the car is plugged?

 

[WFK]

more to try

1. open the heater control! I know it's summer but it's part of the coolant system.
2. I guess the car has A/C. So is it much worse with A/C or it is the same?

 

[max_914]

Hi, Their is a small bleed valve on the engine block where the upper rad hose goes into the engine, bleed the cooling system from their. Also under the carb/intake manifold you will find a "hidden" short piece of heater hose which I'm pretty sure is the output for the water pump. Check and make sure that hose is in good shape it has a sharp bend in it. If it was replaced with regular heater hose it may have a slight kink restricting coolant flow. Also their is a fan on each side of the rad, the one behind the grill is hard to see. Make sure it's working. Good luck

 

[Hamilton Felix]

Just went a few rounds with a friend's '86 Civic Si. Get a new thermostat, and GET IT FROM HONDA! If you buy new from NAPA or another parts house, it will not work correctly.

Just my two cents worth. You might have a different problem. But that weird setup with thermostat in the return hose, requires just the right thermostat, not a generic "close approximation."

 

[Beast]

Well, I hate to be the bearer of bad news but ..... When you said that the overflow will not suck coolant back into the engine, I knew what the problem was. Whats happening is that you most likely do have a head or head gasket going bad. It just has not failed it the spectacular fashion that we all know.( coolant in the oil or steam out of the tailpipe.) Basically you have a leak where the exhaust gasses are leaking into the coolant. This will cause the coolant system to presurize, and not suck coolant back into the engine when it cools. I've seen this several times. If you look at the hose leading to the overflow tank, you will probably see bubbles coming out of the hose from time to time.

Good Luck!