2000 5.0 AWD Coolant Leak Mystery

[smoon63]

:frustrate I am completely frustrated and stumped. I just spent the better part of three days changing the timing cover gasket to stop a leak from behind the crank shaft pulley on my 2000 5.0L AWD Ex. Everything came apart and went back together as expected, and I used up a whole large tube of Permatex on the gaskets for the cover, the oil pan/cork gaskets and the water pump.

I got everything sewed back up this afternoon and started filling the radiator. Before I even got the radiator filled, it started leaking again from exactly the same place as before. I also replaced the driveshaft seal but didn't use the repair sleeve on the driveshaft as it looked to be in good shape. Even so, that would cause an oil leak instead of coolant if I'm thinking correctly. Here's a picture of where the leak is showing itself.

Midas told me they would charge 11 hours labor to do the gasket change, so obviously I would be way ahead of the game - if this had solved my problem. I've read just about every coolant leak thread I could find on here, and thought the timing chain gasket fit the symptoms. Everything is nice and dry topside, all the mess is coming from the driveshaft down. I have obviously missed something, hopefully something obvious, simple, and cheap! Any ideas?

 

[Firetrux]

Lower Intake Manifold Gaskets? When they fail they create a pretty nice leak , and failure is rather common.

 

[smoon63]

Lower Intake Manifold Gaskets? When they fail they create a pretty nice leak , and failure is rather common.

Would it leak even before the engine was started? This is more of a pour than a leak! And it started when I was first pouring coolant into the radiator. I was barely into the 2nd gallon when it started coming out from below the driveshaft. It slows to a drip once the level drops in the radiator, and it doesn't seem to be noticably worse when the engine is running. Of course it could be getting blown around by the fan when running, but it doesn't seem to leak any faster.

Scott

 

[Turdle]

Maybe the timing cover is cracked? Head gasket? Yes, an intake leak could pour out with the engine off.

How bout the stupid water pump bypass elbow hose? That thing can crack on the inner bend

 

[smoon63]

Leak came up suddenly

I forgot to mention in my original post that the leak/pour came on suddenly. I noticed a few drips on the ground last Saturday, and by Monday it was losing a lot of coolant. I changed out the front sway bar bushings last week and thought I might have knocked something loose until I figured out that it was coming from behind the harmonic balancer.

Scott

 

[smoon63]

Maybe the timing cover is cracked? Head gasket? Yes, an intake leak could pour out with the engine off.

How bout the stupid water pump bypass elbow hose? That thing can crack on the inner bend

The timing cover seemed to be in good shape - I didn't notice anything unusual, but I guess it would be hard to see a hairline crack. On the other hand, it seems like it would have to be a big crack to drop that much fluid while filling the radiator on a cold engine. Am I assuming too much here?.

I just put in a new water pump, thermostat and all new hoses in March and everything has been dry up until now. I've watched from the top with the engine running and hot and haven't seen anything running from the top side at all. I changed oil when I did the timing cover and didn't notice any coolant in the old oil, but I'll check the dipstick in the morning to make sure.

Scott

 

[Dan Whitaker]

Just for future reference it is the crank shaft pulley not the drive shaft pulley.

We knew what you meant but if you were to ask the people at the parts store for a drive shaft pulley seal you are going to get the WTF look.

 

[smoon63]

Just for future reference it is the crank shaft pulley not the drive shaft pulley.

We knew what you meant but if you were to ask the people at the parts store for a drive shaft pulley seal you are going to get the WTF look.

Thanks, Dan - I changed it in the original. I've obviously breathed too many anti-freeze fumes this week and it's melted my brain! Driveshaft pulley? Time to go to bed.

 

[smoon63]

Update

Maybe the timing cover is cracked? Head gasket? Yes, an intake leak could pour out with the engine off.

How bout the stupid water pump bypass elbow hose? That thing can crack on the inner bend

More info: Everything above the crankshaft is bone dry, so probably not an upper hose. All the new gaskets arouund the timing cover gasket and water pump look dry as well. There's no coolant in the oil, so most likely not a head gasket or cracked block. Once the coolant in the radiator gets down about 6-7", the leak slows to almost nothing with the engine off. As soon as I fill the radiator back up, it steps back up to a fast steady drip. As before, the drip is always coming off the balancer sprocket and the balancer itself. Everything above that point is dry.

I borrowed a pressure testing kit from Advance, but haven't had a chance to use it yet. What, if anything do I need to do before I hook it up, since the leak is so hard to spot? Remove the fan and shroud? Also, will a pressure test show an intake gasket leak anywhere on the outside?

Sorry for so many posts, but I'm moving into uncharted territory with this one. I've done lots of repair work, but not much of it has involved taking major components off the engine. Suspension, exhaust, AC and radiator replacements aren't as nerver wracking as digging into the guts of the engine. Especially when I've only got my driveway to work in and it's my dailt driver I'm working on.

Scott

 

[windsors03cobra]

Almost sounds like the gasket between the water pump backing plate and the water pump body is bad right at the bottom and dripping right on the balancer.
I know you replaced the backing plate to timing cover gasket but did you inspect the gasket between the backing plate the the pump body ?
What is the condition of the water pump ? Newer ? Brand new ? 145k miles ?
There could be a weep hole on the bottom of the pump shaft that could also piss coolant right onto the balancer.

 

[97-5.0]

the pressure tester is good....just pump it up and look for the leak.....just keep pumping!!


i had to pump over 30psi for my leak to start....
it was a hose that runs into the upper intake that was leaking.....the coolant would run down it then across another hose then finally drip off so just keep looking!

 

[CDW6212R]

I'd look harder around the water pump, and the thermostat housing. It's easy to have the thermostat fall down while installing the housing, which places the T-stat between the housing and the intake.

Keep looking, you should be able to find the source of the leak.

 

[smoon63]

Almost sounds like the gasket between the water pump backing plate and the water pump body is bad right at the bottom and dripping right on the balancer.
I know you replaced the backing plate to timing cover gasket but did you inspect the gasket between the backing plate the the pump body ?
What is the condition of the water pump ? Newer ? Brand new ? 145k miles ?
There could be a weep hole on the bottom of the pump shaft that could also piss coolant right onto the balancer.

I'd look harder around the water pump, and the thermostat housing. It's easy to have the thermostat fall down while installing the housing, which places the T-stat between the housing and the intake.

Keep looking, you should be able to find the source of the leak.

I appreciate all the ideas and advice - the Forum never fails to impress me!

I don't think the water pump is the culprit, although I haven't ruled it (or anything else) out yet. I just replaced it in March, so it's only got about 5-6000 miles on it. When I had it off to change the timing cover gasket, the surfaces were near perfect, and I used black Permatex on both sides of the gasket and let it set up overnight. Also, the leak hasn't changed a bit since before I did all the work changing the timing cover and pump gaskets, which tells me it's probably coming from somewhere else.

In the morning I plan to take off the fan and shroud and the water pump pulley before I run the pressure test so I can see as much as possible back there. I'm hoping it's maybe the t-stat housing leaking. I put in a new t-stat in March, but reused the old housing. Of the outstanding possibilities, that would be one of the easier fixes. Which of course means it can't possibly be the answer!

The pressure test might be unnecessary once I get all the obstructions out of the way. Like I said before, it starts leaking as soon as I get the radiator about half filled. The pressure pump might make it more obvious depending on where it's coming from, though.

I'll report back in the morning after I strip it down and pump it up.

Scott

 

[99SportX]

I am putting my money on something related to the water pump itself. Interesting thread. Coolant leaks are always fun to trace. I look forward to hearing how the pressure test went.

 

[CDW6212R]

I am putting my money on something related to the water pump itself. Interesting thread. Coolant leaks are always fun to trace. I look forward to hearing how the pressure test went.

Hello Eric, long time hasn't it been.

I'll go with you and bet on the wrong water pump gasket being used. Most WP's come with two gaskets, and only one will cover all of the edges right.

 

[smoon63]

The winner is...

I am putting my money on something related to the water pump itself. Interesting thread. Coolant leaks are always fun to trace. I look forward to hearing how the pressure test went.

Hello Eric, long time hasn't it been.

I'll go with you and bet on the wrong water pump gasket being used. Most WP's come with two gaskets, and only one will cover all of the edges right.

Turns out you were both right. It DID turn out to be the water pump, but the pump itself went bad. Even with the pressure tester pumped up to 24 lbs it was tough to find it. Took a while to get the mirror and flashlight at the right angle, but when I got it all lined up it was leaking from the small freeze plug under the pulley. Fortunately it was under warranty since I'd just replaced it in March, so Advance hooked me up with a new one.

Now I just hope I didn't loosen up the brand new timing chain gasket when I pulle dthe pump back off! I'd really be irritated if I had to pull the pump for the fourth time in four months!

For the record, the GMB pump only came with one gasket, and it was a perfect fit both times.

Thank you all for your help - again!

Scott

 

[99SportX]

Glad you got it fixed up. Too bad you had to spend all the time doing the timing cover gasket, but now you know that diagnosing the leak should be the first step.

 

[CDW6212R]

Very good, and yes it's a shame to do work because a part fails that is not old enough to be bad yet.

 

[nameskreen]

i think I have the same problem on my 98. The coolant leaks out almost as fast as I pour it in. I can't really tell where it's coming from, but it looks like it's below the water pump, but not as far back as the timing cover. Is that freeze plug hard to get to?

 

[CDW6212R]

i think I have the same problem on my 98. The coolant leaks out almost as fast as I pour it in. I can't really tell where it's coming from, but it looks like it's below the water pump, but not as far back as the timing cover. Is that freeze plug hard to get to?

How old are all of the coolant hoses? Start by looking harder and finding the leak. I hope it's a hose, those are cheap and easy to replace.