Coolant leak when engine is cold only

[turboplz]

I've got a 99 Mounaineer with the AWD 5.0, 151k miles, only had it for a little over a week now. Today I noticed when I started the engine up (cold engine), I was getting a really good coolant leak coming down from the front passenger side of the engine block. It was dripping about 2 drops of coolant every second.

I climbed underneath to check it out, but I can't get my hand up to the bottom of waterpump to see if it's coming from the weephole and there is really no way I can see if it's coming from the timing cover.

However, when the engine warmed up, there was no more leaking whatsoever. I'm kind of stumped on this one. Is there an easier way to get at the weephole on the waterpump? The truck doesn't overheat, I've been keeping up on the coolant. There is no coolant anywhere else on the engine, just in this general area. Any tips on how to check that area any better?

 

[yavapaires]

I've got a 99 Mounaineer with the AWD 5.0, 151k miles, only had it for a little over a week now. Today I noticed when I started the engine up (cold engine), I was getting a really good coolant leak coming down from the front passenger side of the engine block. It was dripping about 2 drops of coolant every second.

I climbed underneath to check it out, but I can't get my hand up to the bottom of waterpump to see if it's coming from the weephole and there is really no way I can see if it's coming from the timing cover.

However, when the engine warmed up, there was no more leaking whatsoever. I'm kind of stumped on this one. Is there an easier way to get at the weephole on the waterpump? The truck doesn't overheat, I've been keeping up on the coolant. There is no coolant anywhere else on the engine, just in this general area. Any tips on how to check that area any better?

I can't really help you with getting a better look at the waterpump other than to get a mechanics mirror to see the bottom of the pump. But, what I can tell you is that you can have a cold water leak that will seal it self when warm. Large trucks were notorious for that problem before the use of silicone hoses and spring loaded clamps. That being said, check yourhose clamps.

 

[turboplz]

:thumbdwn:

Well crap! I pulled it into the garage today to check the leak out fully. Took off the alternator bracket assembly, piece of cake to do by the way, and sure enough the water is coming out behind the timing cover. Specifically the top passenger side bolt.

Guess since I have it taken down this far I should get the tool I need to remove the waterpump assembly, radiator, fan clutch, etc...

Hopefully this will be a fairly straight forward job

 

[koda2000]

it sounds like a really small leak if it stops once the motor warms up. you could remove the bolt and apply thread sealant to it if you can get to it easily.

 

[Turdle]

Check the small elbow hose off the water pump for a small slit on the inner elbow portion,
This can sometimes spray onto the area you mentioned.

 

[00meangreenXLT]

Ditto on that little hose, mine ruptured just like the picture.

 

[Scout3]

That little hose went on mine too but really only leaked when I reved up the motor. It is a real PIA to change.

 

[turboplz]

It's not that little hose. When I took off the alternator bracket, I removed that little hose and it was fine. The leak continues now, even after draining the radiator, removing the upper and lower radiator hoses. It's definitely coming from that top passenger bolt now that I can clearly see in there.

It's crazy how much it's leaking with the engine off and cooled down. But I guess it's also "small" enough a leak that when the block and cover warm up, the metal expands enough to seal it until the engine cools back down again.

I'm halfway thru the radiator removal, what a PITA that is! Assuming no rusted out/broken bolts, the rest of the job seems pretty straight forward.

Quick question though. Is it necessary to remove the fan clutch from the water pump to do get the radiator out?

 

[Cranmaro99]

The leak could also still be leaking when the engine is warm, it's just that the drip might evaporate if it hits some hot part of the engine. I've seen it, not that it helps or anything.

Prob the water pump, though.

 

[Slofive-O]

Fan Clutch removal

I did this very job a few months back. The fan clutch needs to come off in order to deal with timing chain cover. You can borrow gigantic wrench from local auto parts store. Be prepared for problems with rusted water pump bolts.

 

[1998Exp]

Leaks from the top of the timing cover seal appear to be common with the 5.0L V8 at 100-150K. The gasket is very narrow in that area, and coolant from the water pump passages pump finds its way through them, sooner or later. Unfortunately, when that happens, the bolts rust quickly. Be patient and gentle with them and you may be able to avoid the hassle of dealing with a broken one.
The other challenge of this task is properly resealing the timing cover to the oil pan. The ideal way to do that is to drop the pan - which requires pulling the engine out - so it's not a real option.
Search and you will find several posts describing the job in detail, including one that I posted about a yearr ago.

The hassle of radiator removal can be avoided with the right tools. If you are using an impact wrench to take off the crankshaft bolt, an ultra-compact one will be short enough to fit between the balancer and radiator. Or just block the flex plate by sticking something in the starter ring and muscle the bolt by hand. You will need to do the same in reverse when reinstalling - about 120 ft-lbs of torque are required.
The center bolt on many balancer pullers/installers is too long fit without radiator removal, but you can find them for rent with a shorter one.

In any case, you will need a slim 36mm wrench for the fan nut and a 72mm one to hold the bolts. These can be rented as well.

...

I'm halfway thru the radiator removal, what a PITA that is! Assuming no rusted out/broken bolts, the rest of the job seems pretty straight forward.

Quick question though. Is it necessary to remove the fan clutch from the water pump to do get the radiator out?

 

[turboplz]

Thanks for the tips 98Exp!

I've been reading up the past couple days and will be getting started on it next week. Starting a new job the 2nd, so I definiteantly want to get this situated well beforehand so I can "trust" that I did the job right.

 

[turboplz]

The job is done. Really wasn't all that bad once I got a look at everything. The biggest PITA part of the job was scraping off all the old gasket material! That took me half a day to do with a razor blade and gasket remover material.

Just waiting for the rtv to finish curing at the oil pan gasket, but I filled the cooling system up and no leaks now! Hopefully I got the RTV laid well enough that I won't have oil spewing out.

Hope to never have to do this job again, unwillingly!

 

[Turdle]

You jinxed me--well, I know you really didn't but what a coincidence.

I found this very same leak on our truck. I was certain it was the water pump.

 

[Turdle]

For anyone following this thread:

I went in for the timing cover gasket replacement, however when I removed the water pump I noticed the bolts on either side of the water passage, passenger side, were quite loose. This is where the timing gasket coolant leak was on our truck.

The bolts were replaced with new ones while replacing the water pump only. I used anti seize on the threads, torque them down well and the leak is gone.

However, the new bolts have no "stud" for securing the crank sensor wire harness, so I used a zip tie around the heater hose just to hold it away from the belt and pulleys.


If one of the bolts going into the block seems stubborn, try using an extension on your wrench, and, instead of pushing on it, which will twist it and break it off, tap it with a hammer. Tap it to the right ( tighty) first, then a bit to the left ( loosey) , work back and forth. Keep dong this until you get good movement. One bolt on ours needed to be tapped all the way out using a pipe slid over the ratchet handle as an extension.

If you break one of these bolts it is bad bad news. So, be very careful and take all the time it requires to get it out in one piece.