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Discussion Starter #1 (Edited)
Hey all,

So I got home and was leaking coolant and the car was starting to overheat. It was dark and as the car was quickly running out of coolant, I had only a few seconds to find where the leak was coming from. Looking for the problem from the front of the car, I saw the thermostat housing leaking coolant so assumed the problem was the thermostat.

I removed the thermostat and boiled it in water. The thermostat opened and closed fine, so I thought it was the gasket so replaced the gasket.

I started the car and the leak returned. It was day and was able to see that the leak was actually coming from the heater inlet hose behind the thermostat which had burst and was squirting coolant onto the thermostat housing.

I replaced the heater inlet hose, the leak stopped.

I now have a problem where steam starts to come out of the radiator cap when the car starts to warm up. The heater inlet hose is very hot but the radiator inlet and outlet hoses are only warm, though I don't know what to make of this as steam is coming out of the radiator cap so there appears to be a coolant flow.

I am wondering if perhaps the thermostat is actually faulty despite it opening and closing fine when boiled in water.

Water pump replaced at 296K. Car is now at 380K.
Brand new Toyo (Japanese) radiator clone of OEM radiator installed 11 months ago as well as new radiator cap which appears in excellent condition.

I am praying its not the water pump because if it is then that means its the end of the Prelude but I am not afraid to face an inconvenient truth. At the moment though I am leaning towards the thermostat because if it was to fail closed then that is likely to be the cause of the heater inlet hose to bursting as the heater inlet hose is right behind it.

What do others think?
 

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I am praying its not the water pump because if it is then that means its the end of the Prelude but I am not afraid to face an inconvenient truth.
Its not the end of your Prelude, its just a GREAT REASON to replaced the Timing Belt as well, and go another 100k miles....

Thermostats today are POS....... Ive gone thru TWO each on my Prelude and Accord b4 I finally got good ones... The ones I bought from NAPA

I agree with Dano, its the Thermo
 

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Discussion Starter #5 (Edited)
dao, that is interesting about the water pump not quitting when they go bad. I did not know that. Its good to know. :)
Good to know as long as they are turning, they are pumping. :)


Blainethemono, haha.. no, once this cars odo hits 394K I will be calling the wreckers to come and pick it up for a few hundred dollars. I have had the car for seven years now and I am too big for it. I do have a love-hate relationship with the car, but it does have to go.

I agree that thermostats today are POS. I bought a Dayco thermostat today and it looks like a flimsy piece of crap compared to my genuine Honda one.

The thermostat that appears to have failed now is a Honda thermostat. I bought it five years ago when the aftermarket thermostat failed. I was on the way to my first ever acting gig when it failed and I had to get to the gig at any cost and kept driving 30 kilometres with the temperature gauge on max. I damage my head gasket which is probably why the Honda one has only last five years.

Now you see one reason why I look forward to getting rid of this car. :) Every month I need to fill up the radiator overflow bottle. I also have the infamous oil leak on that thing in front of the distributor. The seal that hasn't been in production for over ten years (37854-PH3-006), I also need to top up the oil everything month as a result of it. This could be one reason why I don't see coolant in the oil. The heater inlet hose also happened to burst right where the oil leak drips on.
The car is in great condition and 100% stock, but the engine is fucked. Its going. Will be getting a 2007 Accord Euro in cobalt blue. :)


Ok guys, so tomorrow I will replace the thermostat and report back the outcome. Thanks for all the re-assurances. :)
 

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WAIT A MINUTE!! Right hand drive? So 394K is in KILOMETERS isnt it? Thats only 244000 MILES!! A drop in the bucket for a Prelude

My Prelude has 210,000 miles and is running like a TOP, and my car body and interior isnt anywhere close to as nice as yours.

Buy a new Engine, redo the head or lose weight.... lol. Preludes can go 400K MILES with proper maintenance.... and clean ones are going UP in value, not down...

and Im konfoosed. P/N 37854-PH3-006 is a dizzy CAP seal. U can buy a used Prelude Dizzy for $60!!. For 88-91 Civic Crx Td-02U Td-18U Complete AssembLED Ignition Distributor Kit | eBay <-- they dropped the price by $140!! and confirmed 89 Prelude fit.

I have 1 in my hall closet right now as a backup, since rebuild Honda Dizzys mostly SUCK. .
 

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Hey all,

So I got home and was leaking coolant and the car was starting to overheat. It was dark and as the car was quickly running out of coolant, I had only a few seconds to find where the leak was coming from. Looking for the problem from the front of the car, I saw the thermostat housing leaking coolant so assumed the problem was the thermostat.

I removed the thermostat and boiled it in water. The thermostat opened and closed fine, so I thought it was the gasket so replaced the gasket.

I started the car and the leak returned. It was day and was able to see that the leak was actually coming from the heater inlet hose behind the thermostat which had burst and was squirting coolant onto the thermostat housing.

I replaced the heater inlet hose, the leak stopped.

I now have a problem where steam starts to come out of the radiator cap when the car starts to warm up. The heater inlet hose is very hot but the radiator inlet and outlet hoses are only warm, though I don't know what to make of this as steam is coming out of the radiator cap so there appears to be a coolant flow.

I am wondering if perhaps the thermostat is actually faulty despite it opening and closing fine when boiled in water.

Water pump replaced at 296K. Car is now at 380K.
Brand new Toyo (Japanese) radiator clone of OEM radiator installed 11 months ago as well as new radiator cap which appears in excellent condition.

I am praying its not the water pump because if it is then that means its the end of the Prelude but I am not afraid to face an inconvenient truth. At the moment though I am leaning towards the thermostat because if it was to fail closed then that is likely to be the cause of the heater inlet hose to bursting as the heater inlet hose is right behind it.

What do others think?
Boiling the thermostat doesn't necessarily tell you it's good. You need to know that it's starting to open at it's rated temperature. I believe OEM is 195°F. I would replace the thermostat with an OEM one (I had lots of problems with aftermarket ones.) If you replace the thermostat, refill and bleed the air from the cooling system (including the heater core, run the engine with the radiator cap off until it warms up, heater on high, make sure you're getting hot air out of the vents.) And still getting steam from the cap, replace the cap.
New parts can fail.
 

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Discussion Starter #10
Blainethemono, yeah I know this car can go on another 100K but if I was to fix everything that is wrong with it I would be half way to another car. :)

37854-PH3-006 isn't actually part of the distributor itself, its some other part of the distributors function. I'm not sure what it does exactly but I'm guessing it has something to do with the overhead cams given location and connection to the motor. I could extract the gasket, have it photogrammetrically scanned and then have a new one printed, but don't care enough. :)


tsiah, that is a good point about boiling the thermostat and when it starts to open at its rated temperature. The aftermarket one is doing its job though and I'm sure it will last till the cars end of life.


spacemaster, thanks mate. If I could afford to, I would. :)


So I replaced the thermostat and everything is good. After this whole ordeal I am not sure there was actually anything wrong with the last thermostat. When I installed this one, the radiator still steamed a tiny bit, but I further bled the engine and it stopped. The shop manual states to bleed it until coolant comes out in a constant stream. The first time around I did this by bleeding for a minute until came to a dribble. I thought this must be the 'constant stream'. When I bled it further I thought I had nothing to lose and really opened up the bleed bolt. Then the 'constant stream' came proper, it bled hard and the revs came down to 800rpm which is correct idle. Who knows, the problem is resolved and is the cooling system is operating to the cars specification. That is all that matters. :)

My only regret is not being able to torque the thermostat housing case bolts. My 1/2 drive torque wrench starts at 28 nM. The torque for the bolts is 12 nM. What ever. I'm broke and can't afford more tools. Next car will be different.

Thanks guys :)
 

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Distributor leaking is easy fix with replacing two seals depending where the leak is. If it leaks from inside the distributor i.e. your leak visible at the dist cap. You can replace the internal seal. If it leaks from the neck joining to the engine head, you can replace it with the external seal. Both can cost around few bucks. I believe it is still available at the dealer.

Search here or DIY section for the distributor seal replacement. I think either Dano or someone else have a DIY. Replace either one of them is easy DIY.

Just to help you with the cost, so you can keep your car LOL.
 
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