Unknown fluid underneath car

Third Generation Honda Prelude topics

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pmg88
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Unknown fluid underneath car

Post by pmg88 »

Hello.

I have a 1989 Prelude SI 4WS- Automatic tranny 157 K miles. I notice that I find
a small puddle of fluid underneath the car after the car has been parked for more than 12 hours. This does not occur just overnight but well into the next day i.e. does not appear the next morning when leaving for work but appears only on my days off when the car has been parked. The fluid seems to be dripping down from exhaust manifold to just underneath the car .It is clear and a bit oily-needing Simple Green to remove it. I've been checking fluids constantly and it does not seem to a noticeable "leak" from suspected fluids.motor oil, tran. fluid, PS fluid, coolant.

I am losing some oil though from what I gather to be a slowly leaking Oil Pan gasket ( noticeable build up on the outer rim of gasket but the mysterious fluid is not oil. it's too clean and clear.Any thoughts would be appreciated.

On a 2nd note- is it too expensive to have someone swap out Oil Pan Gasket?What would that run in US$?

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spiffyguido
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Prelude Model: 1991 SE-SR
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Re: Unknown fluid underneath car

Post by spiffyguido »

Do your brake or clutch fluid reservoirs seem to dip after time?

The way you describe it, it doesn't sound like engine oil. Are you certain that it's dripping down the exhaust manifold? The only other thing I can think of is your axle seals might be leaking tranny fluid.

Regarding the oil pan gasket, you'd have to phone a mechanic to get a price. Not sure what that might cost. Alternatively, if it's a small leak, it may be possible to patch it.

pmg88
Lude Dude
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Joined: Thu Jan 27, 2011 12:34 am

Re: Unknown fluid underneath car

Post by pmg88 »

Thanks for the reply.

No, brake fluid is still at the top level and I am now starting to check tranny fluid. But it seems like it's still OK. This mysterious fluid has been going on for a while. At first I thought it was a coolant leak that was a very slow one but I've been checking the coolant in the radiator and it was not lessening.

Question: what would leak that slowly and take over 8 plus hours to appear? I drove it for some time last night, parked it overnight. Leaving for work this morning,after it was parked for nearly 12 hours, no fluid. If I let it sit for maybe another 6 hours or more, the fluid appears. ???

Can some form of condensation form up after a prolonged time, mix with oil residue and drip down the exhaust manifold? My exhaust sounds pretty loud actually and there could be some crack in it to allow condensation to leak. I know this sound far fetched but with this happening fore time, I do not notice a drop off on performance. Other than the minor oil leak which I've been careful in keeping the revs down, I've no performance issue at all.

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spiffyguido
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Re: Unknown fluid underneath car

Post by spiffyguido »

If there is a hole in your exhaust, that's probably the source of the trouble. Your engine chucks out a lot of water as part of combustion, and if there is a crack for that to get out, some of that moisture might seep out as the exhaust cools and condenses near the hole. That would explain why it looks a little oily and dirty. It would be similar to the moisture that drips out of the exhaust pipe at the back of the car during certain temperatures.

Can you find the hole and potentially confirm it as the source?

pmg88
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Re: Unknown fluid underneath car

Post by pmg88 »

Kind of hard to find anything with Preludes as you well know. Pretty tight engine bay.

I do notice that the fluid was more on very cold days here . Mind you in Northern California in January that would be only in the high 30s or low 40s. Sorry, I notice you're in the Great White North. And the slowness of the leak would be related to when the ambient temperature rises from the lows 40s to 60s.

Side question: I do notice a rough idle after restarting the car after its been parked for a short time i.e. driving to supermarket, shopping for 20 mins, and then restarting car. Notice it idle roughly and have to rev motor a bit. Once car is moving its OK. I notice this really started happening when ambient temp was cool.
Is this related to suspect leak or is this more to do with Idle Air Valve sticking? ( your
posted article on common Prelude problems)

Thanks.

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spiffyguido
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Re: Unknown fluid underneath car

Post by spiffyguido »

A leak on the exhaust side wouldn't cause idle problems like that.

It could be the IAC valve (if it's stuck in a position), but usually IAC valve problems cause a bouncing idle.

Can you further describe the 'rough' idle. Does it burble and try to stall? Does the idle fluctuate? Does it just idle really low (<600rpm) and cause the car to shake a bit?

pmg88
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Re: Unknown fluid underneath car

Post by pmg88 »

Sometimes if I changed to D ( it's automatic) without revving it up, stalls. This happens when the ambient tempis really cold, i.e early morning. It does burble and rev low so much so that I have to rev it up a bit. Sometimes if I fear that it would stal, I two foot it ( Right foot on gas, left foot on brake - Go Cart style) to catch it it looks like it will stall. Previous car I've owned had something similar where it would burble and stall on a cold start. ( Mechanic who fixed it said it was the Cold Start Valve and that it was dirty- a common problem with Mitsubishis). Does a Prelude have something similar ? Is that what the IAc valve is? Could it get stuck on a cold restart and revs get it out of the stuck position? Is it a dirty valve or is it a Remove and Replace?

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spiffyguido
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Re: Unknown fluid underneath car

Post by spiffyguido »

It could be the IAC being stuck.

Before you look into that though, you should make sure the idle is set correctly to begin with. It might be that your idle is just set too low, causing another sensor to compensate. This would explain why it has trouble when the engine is loaded up in D. Ordinarily the engine should compensate for you shifting it into drive, but if the car has trouble, it's as if your engine has lost its ability to further compensate, potentially caused by the sensors already being fully taxed.

There is a detailed procedure in the service manual (see manuals section) that described how to set the idle properly. If you idle is good, then we know the trouble is coming from the sensors, and not the other way around.

pmg88
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Re: Unknown fluid underneath car

Post by pmg88 »

Thanks, I'll check the idle before checking the IAC.



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