Alrighty, my mom has a 2002 Grand Prix GT. It's leaking coolant pretty bad. As in a gallon a week or so. I have no freaking clue where the coolant is going! There is a small wet spot under the water pump, and the pump is a little noisy, but I doubt it's losing a gallon a week there. After heavy driving the water pump felt dry anyway. I've read a LOT about intake gasket failure on 3800's, and due to a similar issue on our 2.8's I'm kinda familiar with that. Checked the oil, it isn't milky or foamy, and there is no coolant smell. Phew. Coolant reservoir smells awful, but I can't tell if there's oil in it because the p.o. was kind enough to dump stop leak in it. Ugh. There is all sorts of oil leaking from the upper intake manifold, so much that there is a neat oil stain over the back half of the trans. There was oil leaking from the throttle body into the intake hose to the filter box!!! This leads me to believe that the upper intake manifold gasket has gone, leading to oil leaking externally and coolant leaking into the cylinders and being burned off, being why the coolant is just disappearing. Does that sound possible? Likely?

Also after the car has been running, if the engine is shut off for a minute and you try to restart it it has a hell of a time starting. Coolant pooling in the cylinders maybe cause that? I'm supposed to "take care" of this this morning but after some diagnosis, I'm back at square one. My dad's solution was just replace the water pump but he knows far less about cars than me and I know that water pumps don't usually leak that bad.

Any input guys? Thanks!

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(TRSX) The Zombiero - "Thrice resurrected"
1985 GT, 4 Speed Muncie, 3.4PR V6, 15" Lace GT wheels, Power everything, sunroof, Red with gray effects. Driven and enjoyed daily.

Fiero GT- 2 seater, mid engine, rear wheel drive, H.O. V6, manual rack and pinion steering, fully independent suspension, 4 wheel disc brakes, no ABS, no traction control, no speed limiter, available T-Tops. So, outdated econo-box or classic sports car? You decide.

have someone follow you around the block, stomp on it and see what the exhaust looks like

I've driven behind the car a few times and I never saw any funny exhaust but it did smell weird. I really think that the coolant is burning off but I'm not sure if the UIM is to blame. I hate doing things twice...

There are two plastic elbows that feed the heater core. They are buried under the alternator and its bracket. I can almost guarantee you they are cracked or the o-rings are leaking. The intake to head (LIM gaskets) are also a common failure point. It would be a major leak if within a minute it is hard to restart because of coolant leaking into the cylinders - you would be seeing white smoke out the exhaust.

[This message has been edited by FrugalFiero (edited 09-29-2011).]

quote Originally posted by FrugalFiero: There are two plastic elbows that feed the heater core. They are buried under the alternator and its bracket. I can almost guarantee you they are cracked or the o-rings are leaking.

I read that as well. I'll check inna sec.

Weep hole under the water pump. start it up and before it warms up to operating temp shut her down. get a small inspection mirror and look under the water pump. chances are that is it if the water pump is making noise.

Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't.

Detroit iron rules all the rest are just toys.

quote Originally posted by 84fiero123: Weep hole under the water pump. start it up and before it warms up to operating temp shut her down. get a small inspection mirror and look under the water pump. chances are that is it if the water pump is making noise. Steve

I'll do that now.

You think it could leak a gallon a week?

Maybe run it for 15 minutes, and THEN follow it around the block? (maybe the leak gets 'worse' as the engine heats up?)

quote Originally posted by TheRealShadowX: Well those are both dry. You're right, they are tucked away pretty good.

They can leak under pressure, and feel dry when not.

How many miles on the GP? This is what the LIM gaskets looked like on my 99 GP GTP with 100K miles. It would be hard to start and white smoke billowing out the exhaust if it sat for a week.

I agree with the posted sugestions.Could allso be the water pump.I once had a high milage pump, dripping water through the weep hole at the bottom of the pump, (near the pulley), but you would be getting a small amout of water on the pavement,most of it being lost while driveing.I once saw a truck with a very small pin hole in the radiator tube (probubley caused by a small stone), well it was pissing the coolant ,in a fine mist, down the road.You might try some coolant tracer dye, might be called just tracer dye.I think you need a UV light (some are L.E.D. Now).

Update!

150k on the GP GT.

Parked it over a dry patch of concrete and let it run. Fairly heavy drip from the back of the engine. If I'm not mistaken the A/C is at the front. Only reason there is any confusion is because my parents filled the coolant 100% with water so that REALLY helps diagnosis. Lol. So I'm going to pull the Alt. and inspect further.

I'll keep this thread VERY active this morning. I work for my dad and today he gave me the day off from real work and gave me fixing the GP as my task. Hahaha. Today is gonna suck.

quote Originally posted by TheRealShadowX: Of the 2 platic elbows, one is obviously visible just forward of the idler bracket. Is that the upper or lower? I can't rule those out just yet. The felt dry but the car was sitting for a bit when I felt. After seeing that leak coming from that side of the engine I'm not so sure.

You pretty much cannot see (or feel) both plastic elbows without at least removing the alternator.

quote Originally posted by FrugalFiero: You pretty much cannot see (or feel) both plastic elbows without at least removing the alternator.

Alright. That's the first step when I get a dry moment.

Check the little plastic 90* elbow that connects the lower intake manifold to the accesory belt mount. that mount has coolant passages for the heater core in it. It is on the passenger side of the car above the water pump. mine cracked under the O-rings and leaked a small amout of coolant . I pulled the lower intake manifold to fix it and for good reason.The LIM gaskets looked like the pics above, and a few of the bolts had lost torque.

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ARCHIES JUNK IS FASTER THAN SHAUNNA'S JUNK
12.3 is faster than a 13.2

Yeah those are the ones. If it ever stops raining I'll be checking those right away.

As far as the gaskets go I don't think I'll be doing those. Not now anyway. How long does that whole job take anyway? 4-8 hours depending on skill level?

The entire upper intake (the plastic part) goes bad and causes this. At least that's what my GP GT did a few years ago. The Dex-cool goes bad, turns into acid and eats everything up. You can tell if it's bad by smelling it. It will smell like a dirty wet dog in the overflow tank. It will also leave nasty, grey, sandy deposits everywhere. DO NOT put that crap back in when you fix it. Go with good old green antifreeze.

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1986 SE 350 V8

Well, yesterday kept on raining so I'm back at it today.

Snapped a pic. I can only see one 90* bend. Where is the other one?



EDIT: I circled the one I can see in red.

[This message has been edited by TheRealShadowX (edited 09-30-2011).]

I think you are going to need new LIM gaskets.

Also, the UIM can develope a leak aroung the egr stove pipe. It melts the plastic UIM where the egr stove pipe passes through and opens the coolant port in the UIM to intake vacuum, causing the coolant to be burnt in the engine and sometimes hydrolocking the engine durring start up. There is an updated LIM with a smaller stove pipe that stops this from happening, you may already have the updated LIM and won't need to worry about this.

When you do LIM gaskets, it is recommended to do the plastic elbows at the same time. They can be accessed by removing the alternator bracket. Make sure to get all of the old elbows out because they usually break off and leave a piece behind in the hole.

Edit: The other elbow is kind of behind and under the belt tensioner pulley.

[This message has been edited by 1fatcat (edited 09-30-2011).]

Ugh, yeah probably going to need new gaskets.

I found the other elbow, it was right in front of me lol.

I'm off to get some of that mechanics dye to try and track down the leak. One of the elbows was wet and has clearly been leaking but I can't get it to leak on cue it seems.

quote Originally posted by TheRealShadowX: This leads me to believe that the upper intake manifold gasket has gone

Probably it. I've had a 3.1, 3400, and 3800 and they all did it.

Mechanics dye shows a pretty hefty leak at one of those 90* elbows. $4 gets me 2 new ones.

quote Originally posted by TheRealShadowX: Mechanics dye shows a pretty hefty leak at one of those 90* elbows. $4 gets me 2 new ones.

The would be awesome it that was all it was.

quote Originally posted by 2.5: The would be awesome it that was all it was.

Shhh!!! You'll jynx it!