Overheating Prelude

[Glaslegacy10]

My Wife's 90' Honda Prelude overheats at idle. The radiator and fan were replaced about 10,000 miles ago with factory parts. At first the fan wasn't coming on. I replaced the fan switch, coolant temp sensor, and relay. The fan worked, but the car was still overheating at idle. There is no sign of leaking anywhere. I flushed the radiator and replaced the overflow container "found cracked". Its still overheating at idle and the fan won't come on again? Help!!!

[rivolette]

I'd suggest you replace the thermostat next. Quite possibly the culprit.

[Glaslegacy10]

I forgot to mention that I replaced that also. That was the first place I started. Thanks though. Any other ideas?

[larsen_huw]

Do you have any symptoms of a blown head gasket?

These modern engines are rather fragile and overheating them once can blow the head gasket which causes yet more overheating problems.

[rivolette]

These modern engines are rather fragile and overheating them once can blow the head gasket which causes yet more overheating problems.

lars, I'm gonna have to disagree with you on that bud. The sheer abuse that I've put my last 3 vehicles through (all newer Japanese cars, 95 Honda, 98 Toyota and 2000 Nissan) is not even remotely comparable to how I would drive my early 1980's big block Chevy. It was always pampered, never drove it over 60 mph and all the works. You know...

And still, the newer ones seem to hold up better with no symptoms of failure. I think it has to do with more precision cut parts in the engine as well as new materials that are lighter.

Try revving up a newer Honda or Nissan engine to 6000 rpm, then try doing that with an older car, it'll fall apart in no uncertain terms.

Anyways, just my 2 cents.
Cheers ;)

[larsen_huw]

Oh really?

So my mid 1970's engine that i regularly rev to 7500rpm should have fallen apart by now? :)

More thinking materials than design .... cast iron holds up one hell of a lot better under heat than aluminium. I've run a cast iron engine for 50 miles with no fan belts ... water pouring out the radiator, oil pouring out of everywhere oil can pour out of an engine. Then just waited for it to cool down, fitted a new fan belt and drove off as if nothing had happened.

They don't make them like they used to! :)

(Yes, I'm a tecnical luddite who seems to have become a whining old fart at the grand old age of 21! :D )

As for Chevy engines .... you yanks have never been very good at engine design! :p You just make it bigger until you get the bhp you were looking for! :D

[rivolette]

As for Chevy engines .... you yanks have never been very good at engine design! :p You just make it bigger until you get the bhp you were looking for! :D


Ouch, that really hurts coming from someone who drives a "FORD" dude. You're right, they don't make 'em like they used to and boy am I glad they don't. ;)

[larsen_huw]

Well my Ford was designed in the UK and bolted together in Germany.

Luckily you yanks had nothing to do with it! ;)

And while my engine is called a 'pinto' ... it bears little resemblance to the American version.

I reckon we're just gonna have to agree to disagree on the old/new debate! :)

[rivolette]

It's not like Brit cars are the reliability beacon in the automotive industry either lars. Look at Vauxhall, you'd be better off walking, or the notoriously unreliable Land Rover Discovery. Even the high end stuff, like Rolls etc... You can pick up a decent brand new Chevy for under $20k, and it still outlives anything that rolles off the Vauxhall assembly line.

[larsen_huw]

Very true.

I don't trust modern cars ... too much to go wrong! :)

If you did force me into a modern car, it'd almost certainly be Japanese.

If you can't fix it by hammering it until it works, i don't want to know. :D

btw ... call me Huw .... it's my name ... Lars was my great-grandfather.

[Glaslegacy10]

There doesn't seem to be any oil leaking around the heads. I checked the oil. The level has been consistant and there doesn't seem to be any water in it. If there are more symptoms that I'm missing please let me know. Thanks.

[larsen_huw]

Oily residue in the expansion tank and a white mayo-like substance in the oil (usually under the filler cap).

[Glaslegacy10]

I had to replace the overflow tank so I couldn't tell you there, but there was nothing else suspicious.

[larsen_huw]

OK .... in that case there probably isn't any problem with the head gasket.

Have you thought about fitting an aftermarket fan .... possibly one with a manual over-ride switch in the cabin?

oh! final point .... i know it sounds daft, but you do have coolent in the radiator mixed with water, not just water on its own?

[Glaslegacy10]

The water is mixed with coolant at a 50/50 ratio as per the Chilton's guide. As far as a new fan, they run about $200. I was really hoping the problem would be be somewhere else. The fan in there now was working after I changed the fan switch. I don't know why it stopped again.

[tich]

Seems this thread got a little hijacked in the middle. But for my opinion give me an older cast iron engine any day over a modern hi tech hi aggro engine or an american overgrown lump either. Agree they make it bigger until it ends up with somewhere near enough bhp (even though its then so heavy it needs more just to pull its own weight along) !!!!!

But on a more serious note I would want to take a look at the water pump if it was mine. Sounds like either the water is not going round well (pump) or cant get round (blocked waterways)? Have heard of impellors wearing away on pumps and not pushing water at low speeds.

[Glaslegacy10]

The water pump is the only thing "I think" that I havn't replaced, however I was told by several people that if the water pump is bad it will leak. The car doesn't leak anything at all. Its tight as a drum. The wife is getting really upset because its not fixed yet. Help!!!!!!!!

[larsen_huw]

Water pump doesn't explain why the fan isn't cutting in.

Even at idle there should be enough water in the system to trigger the thermostat.

But yeah ... if the vains were worn down in the water pump, it would have a serious knock on effect on the rest of the cooling system.

[Glaslegacy10]

ok so if its the water pump, how can I tell it is bad? I've been told it leaks when its bad. This car doesn't leak at all. I don't want to spend $75 on a pump if thats not it. I've already spend about $250 and havn't fixed anything. Is there some test I can run or signs to see if the pump is bad?

[tich]

Ok, firstly pump will only leak if internal seal has gone. if impellors worn it just means pump is inefficient. Only way to sort this without spending loads is to have a good look at a new pump paying attention to the vanes that drive the water and compare to condition of pump on your car.

You then have the problem if the pump is ok that either the water is not circulating because of blocked waterways (need heavy duty cooling system flush) or failure of fan switch, fan, thermostat or mis reading gauge.

Would also suggest removing thermostat altogether if possible and run engine like this to see what happens to temperature.

Keep posting as you go along.