[sully56345]

I have a 99 intrepid 3.2 and every time I fill the coolant, the next day, the recovery tank is almost empty. With just a smidge left at the bottom. Is my tank leaking? I can’t find any leaks anywhere

Also a few months back I’ve replaced the radiator, as the factory one developed a crack at the seam

 

[peva]

No drips from back of engine? One hidden leak point that can develop in the 3.2/3.5 is under the lower intake due to a bad o-ring where the heater core supply pipe plugs into the lower intake. Coolant would collect in the V between the heads and proceed to the back of the engine and drip down the back of the engine.

Another hidden leak point is the two donut gaskets (rings) that seal the water pump inlet (outlet?) ports of the right rear timing cover to the front of the engine block. The two gaskets deteriorate and the mating surfaces of the block badly corrode - leak develops - coolant may evaporate before dripping to the ground. Not easy to fix. People have been known to grind out the corroded/pitted metal down to clean metal and fill in and recreate the mating surfaces using J-B Weld (see post nos. 23, 24, and 26 here - skip thru the oil pump photos in post no. 23: 3.5 Rehabilitation Thread).

Can we assume you don't gave a head gasket problem?

Another phantom coolant loss place is the coolant reservoir. When they get old, the plastic gets brittle and can develop microcracks thru which coolant seeps and evaporates without dripping. When this happens, it's generally not too long before a true crack develops and it looses pressure and dumps your coolant. (If you replace the reservoir, do not get an aftermarket one even though they are a bit cheaper - they are made of inferior materials and don't last long at all. You might find new OEM ones on ebay. Rock Auto lists them - 4758269AB - but are currently out of stock.)

Another possible scenario is either the transmission or engine oil cooler tubes inside the radiator developing a leak. I forget when this happens if generally coolant moves out of or oil or ATF moves into the coolant system when this happens.

Those are the places that come to mind.

 

[yevrah]

fill the resevoir up to full on a cold engine, replace cap, start it up with the hood open, and start watching for any leaks.
has this happened only a few times?
might still be removing air from the rad replacement?
under intake, at the head and lower intake.
water pump, and coolant return tube from back of engine to thermostat housing.
all are common places for coolant leaks.
and the resevoir tank can crack, leaking under pressure.
take a bit of work from you to figure it out now.
hope you find the problem.

 

[sully56345]

This has only happened just recently and a few times. Head gaskets are good. No smoke out the back, no bubbles in the coolant tank, oil is good.

radiator was replaced sometime around July-august.

 

[peva]

Got it. You're probably right, but aftermarket radiators (and other parts) have been known to be bad right out of the box. Happened to me once on a radiator replacement (leaky solder joint).

 

[sully56345]

Wish these cars gave you more room to work with lol. I did have it running with the hood open a couple days ago and couldn’t see any leaks at all. Granted I’m in Minnesota and there’s snow all over right now, so whatever water I drove in and or slush, is dripping from the bottom frame.

so that makes it harder to find a steady leak that’s coolant.

I can’t remember what brand of radiator I bought. I spent 140 bucks on it from O’Reillys.

I also did look for any leaks near the seams and bottom passenger side of the radiator, besides what I believe is water, everything looks fine.

I also drove it around for an hour, stopped at a gas station and checked the coolant and it didn’t look like it went down. I had opened the cap (idk if I have a bad cap or not, but there’s never any pressure built up?) and the coolant looked to be pretty high.

 

[sully56345]

My coolant just refilled itself to the top??? I’m guessing there was still air trapped in the system somewhere? Or I just didn’t have enough coolant previously and it’s finally full? I realize our cars use more coolant than a lot of others. My previous Chevy venture only used 1 gallon. This one took like two bottles of coolant over the past months

 

[sully56345]

So it is leaking. When I look under the car towards the back it’s dripping. But from the top of the engine it looks dry.


My guess is what peva said. Probably the o ring for the heater core.

Question is, how would go about fixing that?

 

[peva]

So it is leaking. When I look under the car towards the back it’s dripping. But from the top of the engine it looks dry.


My guess is what peva said. Probably the o ring for the heater core.

Question is, how would go about fixing that?

You would need to remove the plenum and lower intake. The heater core supply tube plugs into the underside of the lower intake, sealed by that o'ring, which is a common failure point.

 

[sully56345]

Do you have any part numbers for the o rings I can use?

 

[peva]

Do you have any part numbers for the o rings I can use?

Chrysler P/N 06505692AA (when searching Chrysler part numbers with a leading zero, try with and without the leading zero - some data bases only recognize it with the zero, others only recognize it without the zero)

I came across one post that said it had been replaced by 68164687AA - have not been able to confirm.

ALSO - there have been a few instances of the metal heater supply tube itself rusting thru. You won't know which is the case until you remove the lower intake. Hopefully it's just the o-ring, and your tube is in good shape - probably hard to find and expensive.

 

[sully56345]

I wonder what the size of the o ring is? And I’m probably going to have to order new gaskets for the lower intakes and up. I’m hoping the pipe is good.

I’ve seen problems where the heater pipe by the driver cat can get a hole in where it turns up towards the back of the engine.

When I bought the car, it had little to no rust. And everything was taken care of. For being a Minneapolis car where there’s salt galore all over the roads during winter, I only have minor rust under the doors(common spots on these cars)

 

[yevrah]

you'll need a lower intake gasket set, as you'll need to remove it to get to the o-ring.
o-ring will probably come with the kit.

 

[rays04]

So it is leaking. When I look under the car towards the back it’s dripping. But from the top of the engine it looks dry.


My guess is what peva said. Probably the o ring for the heater core.

Question is, how would go about fixing that?

What side is it leaking from?

 

[sully56345]

Back of engine. Hard to tell as I can’t fully see. But it’s as peva said, it’s dripping towards the back, from the bottom.

Keeping a thing of coolant in the car for now, as it’s fricken cold out and I don’t have heated garage. And I’m in mid minnesota.

I’m looking at fel pro gaskets, around 30 bucks. Comes with two o rings? So I’m guessing that’s the heater o rings?

 

[peva]

Not sure what the generic o-ring size the part is. I tried to search and discover if anyone on DI-net forums has ID'd and posted the generic size, but if they did, I couldn't come up with the magic search terms to find any such thread/post. I was thinking that it had been posted at some point in the forum history - maybe so, but maybe not.

What Felpro gasket set number are you seeing? If it's Fel-Pro MS92165 (see photo below), I'm pretty sure the two "donuts" are the rear timing cover-to-engine block gaskets - not o-rings per-se, and not the heater tube-to-LIM o-ring (if so, not sure why they're in the LIM gasket set - perhaps just poorly named grouping).

Fel-Pro MS92165 (I'm thinking the blue thingies have nothing to do with the LIM or heater supply tube):

Anyway - I may be looking at the wrong Fel-Pro set and way off in left field - therefore, please post the Fel-Pro P/N that you're talking about so we can be on the same page.

I also see a Fel-Pro MS91990 upper plenum set with the same two donuts - again, they appear to be the two rear-timing cover-to-block gaskets, in which case, again, strange grouping/naming by Fel-Pro.

EDIT: Apparently the blue donuts are the LIM joint "o-ring". Not sure why they show 2. See post no. 18.

 

[sully56345]

That gasket set you posted is the exact set I was looking at. Pretty much the ones you mentioned are the ones I’ve looked at but Fel Pro names so many of these differently, it’s weird to make a decision.

 

[peva]

Post no. 5 in this thread may clear things up: Coolant leaking/Need RTV for lower intake manifold gasket?

See the 3rd photo (also posted below) showing the Fel-Pro "o-ring" and a generic size 116 (in viton) o-ring that the author apparently successfully substituted.

So apparently the "o-ring" in the Fel-Pro kit is the correct one (why do they include two?). It is a flat-cross-section donut rather than a generic-size round-cross-section o-ring.

I tell you - that is a crappy design - relies on the end of the heater core supply tube pressing with just the right amount of pressure against the o-ring rather than an actual o-ring inserting into a hole and the end of the pipe inserting into the o-ring ID for a precise interference fit.

From linked thread - Fel-Pro gasket on left, 116 o-ring on right that possibly will substitute - not sure I'd expect it to be any more reliable than the flat factory or Fel-Pro gaskets. Silk purse - sow's ear...:

 

[peva]

(deleted post - duplicated by mistake)

 

[sully56345]

Jesus, agreed that is a crappy design. From the looks of it, in case pressure wasn’t enough to hold the o ring in place for a long period of time, that guy put RTV around it as well, as a secondary precaution.

Don’t blame him, as tearing the top half of the engine off, every time that o ring failed, would be a pain in the ass.

What I might do is order the Gasket set but also the generic o ring as well, just in case.

I also hate how the heater pipes in this engine are set up. Guessing that’s one of the negatives of having the engine face forward as if its a rwd