97 Burb w/coolant leak

So a few days ago I started to notice a coolant smell then I noticed the coolant starting to leak, but only AFTER the engine is turned off. Up to a pint will leak out after the engine is shut down. It appears that the hoses are intact and are not leaking and the drip runs off of the bottom belt pulley, close to where the bottom hose joins the motor. It has been hundred or so degrees here in Moab the last week...

I recently had the radiator flushed and the pressure in the radiator stayed high, so no apparent leak in the radiator.

I could certainly use some help...thanks!

So a few days ago I started to notice a coolant smell then I noticed the coolant starting to leak, but only AFTER the engine is turned off. Up to a pint will leak out after the engine is shut down. It appears that the hoses are intact and are not leaking and the drip runs off of the bottom belt pulley, close to where the bottom hose joins the motor. It has been hundred or so degrees here in Moab the last week...

I recently had the radiator flushed and the pressure in the radiator stayed high, so no apparent leak in the radiator.

I could certainly use some help...thanks!

Is the intake gasket leaking?
Check oil for coolant in it.
Run a pressure test cold and warm and the hot and see if any leaks or lose of pressure.
For the hard to find leaks they make a coolant dye to help aid in finding the leak.

Got a better look at it today (in the light and the drip is coming from under the water pump---no movement in the fan, though. Is this typical with a bad water pump?

Thanks MT-2500 for the intake gasket advice---no oil in the coolant...whew!

If it is running or dripping out of the water pump weap hole it is a bad water pump.

But also keep a close eye on intake gasket they can leak external or drop coolant in the oil.
Fix water pump and run a pressure test to be sure you got the leak or all leaks.
Go brand new on water pump not rebuilt.
Good luck
MT

I just dealt with this problem on my 97 K2500. According to the GM manual, after changing antifreeze (you mentioned a flush) one needs to install two sealant pellets obtainable from the dealership. I thought this sounded silly--why would a good water pump leak when exposed to the expensive special antifreeze, but it really solved the problem.

GM makes a couple different sizes of these. I went and asked for the pellets and the guy handed me a package of them. The part number wasn't the one given in the book. He muttered something about a changed number but looked anyway. He had the correct part number and they were bigger than the ones he originally offered. The seem to be made of crushed almond shells and other 1920s technology.

It saved me installing a new water pump which was my normal solution to one that leaks at the seal.

I just dealt with this problem on my 97 K2500. According to the GM manual, after changing antifreeze (you mentioned a flush) one needs to install two sealant pellets obtainable from the dealership. I thought this sounded silly--why would a good water pump leak when exposed to the expensive special antifreeze, but it really solved the problem.

GM makes a couple different sizes of these. I went and asked for the pellets and the guy handed me a package of them. The part number wasn't the one given in the book. He muttered something about a changed number but looked anyway. He had the correct part number and they were bigger than the ones he originally offered. The seem to be made of crushed almond shells and other 1920s technology.

It saved me installing a new water pump which was my normal solution to one that leaks at the seal.


Welcome to AF

GM tabs or stop leak is only a band aid on the main problem.
If a water pump is leaking it is bad and should be replaced.
Even if the gm tabs or stop leak will stop it for a while it is still bad and will go out later.
When a pump leaks it will also damage the pump bearing from cooling going threw it from the leak.

A new water pump now is a lot cheaper than a new engine later when the water pump blows later and burns up engine or the fan goes threw the radiator.:grinyes:
MT

MT-2500:

That's the conventional wisdom. I'm an import (German) tech and had never heard of putting stop-leak in except as a temporary patch until the job could be done right by replacing the failed part. Not since the advice to put a handful of ground white pepper into the Model T radiator had I heard of an application where it is normal to put in stop-leak.

When this happened on my truck (Germany doesn't make anything that will tow my 4000lb trailer!) I read the factory manual to familiarize myself with the steps for replacing a water pump. In the official GM manual it stated that any time the antifreeze is replaced, the stop-leak must be installed to prevent leaks. It wasn't advised just in case of existing leaks, but for prevention, even with the installation of a new pump.

I had changed antifreeze and within a couple of days I got seepage at the water pump. The WP bearing had no significant play, but I bought a new WP and, before replacing it, read the book. I bought the pellets and within a couple of days of installing them, the leak stopped.

I still have the WP and will install it some time this summer. From the feel of the bearing, I don't think I'm in any danger of putting my fan into the radiator.

Are there any factory trained GM techs who can weigh in on this recommendation in the manual? Is it standard to put the sealant into the system with each antifreeze change? Is the book right or wrong? Will WP seals fail if the pellets aren't installed? (Mine reinforces that idea.) If the seal starts to leak due to lack of the pellets, is the problem reversible with the addition of the sealer, or is the seal damaged permanently, requiring WP replacement?

(Just a thought--If the place that did the flush didn't put in the sealer pellets, are they liable for the failure of the WP?)

Glad to find this forum! As you can see, I have some questions about the things I'm finding while caring for my behemoth. As I tackle maintainance and problems I'll probably find some differences between this vehicle and the ones I normally see.

MT-2500:

That's the conventional wisdom. I'm an import (German) tech and had never heard of putting stop-leak in except as a temporary patch until the job could be done right by replacing the failed part. Not since the advice to put a handful of ground white pepper into the Model T radiator had I heard of an application where it is normal to put in stop-leak.

When this happened on my truck (Germany doesn't make anything that will tow my 4000lb trailer!) I read the factory manual to familiarize myself with the steps for replacing a water pump. In the official GM manual it stated that any time the antifreeze is replaced, the stop-leak must be installed to prevent leaks. It wasn't advised just in case of existing leaks, but for prevention, even with the installation of a new pump.

I had changed antifreeze and within a couple of days I got seepage at the water pump. The WP bearing had no significant play, but I bought a new WP and, before replacing it, read the book. I bought the pellets and within a couple of days of installing them, the leak stopped.

I still have the WP and will install it some time this summer. From the feel of the bearing, I don't think I'm in any danger of putting my fan into the radiator.

Are there any factory trained GM techs who can weigh in on this recommendation in the manual? Is it standard to put the sealant into the system with each antifreeze change? Is the book right or wrong? Will WP seals fail if the pellets aren't installed? (Mine reinforces that idea.) If the seal starts to leak due to lack of the pellets, is the problem reversible with the addition of the sealer, or is the seal damaged permanently, requiring WP replacement?

(Just a thought--If the place that did the flush didn't put in the sealer pellets, are they liable for the failure of the WP?)

Glad to find this forum! As you can see, I have some questions about the things I'm finding while caring for my behemoth. As I tackle maintainance and problems I'll probably find some differences between this vehicle and the ones I normally see.

I think you are confusing the intended use of the tabs.
Tabs in some GM engines they are more for head gasket sealing and pin holes in metal casting and stuff like that.

But I have not say them called for on the chev 4.3 V6 or the 5.7 V8

Any shop that does a flush is not liable for leaks after the flush.:grinyes:
On certain GM engines that call for the tabs they should use them.
Why would they be liable for a leak after flush?

MT-2500,

What you say makes sense. As I said, I'd never heard of a modern engine needing a sealer in addition to the regular antifreeze. (Some of the early Volvo 960 series had porous blocks that wept coolant but Volvo issued a repair bulletin indicating that changing the block was the proper repair.)

I'm troubled by what caught my eye in the 1997 C/K truck service manual Book 1 of 2 (no publication information, it appears to have been printed for the Service Technology Group of General Motors and was purchased through a dealer).

In the Cooling and Radiator section, page 6B-15:

"NOTICE: Two sealant pellets GMSPO P/N 3634621 must be added to the radiator whenever the coolant system is drained and refilled with fresh coolant. Failure to use the correct sealant pellets may result in premature water pump leakage. Do not add pellets to the coolant recovery bottle since this may prevent coolant system from operating properly."

This is what led me to buy the pellets and install them after developing a WP leak right after a coolant change. I'm skeptical, and will still change the WP when I get a chance, but I can't help but notice a link between the pellets and the leak. This paragraph was also the basis for my wondering about liability on the part of the shop that did the flush if these instructions are valid and they did not follow them.

I was trained to read the factory service information and have learned that failing to do so can lead to some unexpected and often unpleasant results. I also know that in ten years a lot of new information comes out and that what is in the manual may have been superceeded or corrected. (Some manuals have more errors in them than a KC Royals game!)

At this point surfmonkey probably gathers that a WP change is a good, conservative approach to stopping the leak. That's the direction I'm headed in, too. My burning question then is: Is the information in my manual correct, superceeded, or just overly conservative and generally ignored by the techs who work on these vehicles daily. What do GM shops currently do when they flush a system? Was it just a coincidence that I got a leak after a change and it went away when I added the pellets? I've seen stranger things....

If it is in the GM book I would go by the book and do it.
I use Mitchell On demand repair info which is usually a copy of the GM service manual with the same info.
But I can not find anything in Mitchell on it.
I have ran into using the tabs on some of the bigger GM car engines but I always figured it was more for head gaskets and porous heads and blocks.

You might check other years GM manuals and see if it is in them to or just something on the 97.
Or question the GM dealer tech's about it.
Good luck
MT

I had a Buddy with All Data check it out and here is what All Data says about it.
http://www.batauto.com/Forums/index.php/topic,3022.msg17451.html#msg17451

Looks like it is a one year one model deal.
But interesting info a couple of post up there.
Look like the tabs can make the coolant explosive/combustible under certain conditions.

MT

MT

Glad that's all figured out! I, of course, had to get the one strange model.

I've never heard of such a thing anywhere else. Of course this makes me wonder, what's special about that particular engine, WP, or seal? Must have been some sort of problem--I can't picture engineers deliberately designing things that way.

The GM parts guy didn't look at me like I'd lost my mind when I asked for them. He actually had two different packages of pellets, one smaller than the other. They must use them in some other application.

I appreciate your taking the time to check into this. And thanks for the pointer to the other forum. I'm just starting to learn about these iron-engined creatures and the more places where I can read and ask questions, the faster I'll learn.

Check out this link to getting the fan off. I tried it and in 30 Sec it was off!
Dang good idea of large channel locks holding the pully:grinyes:
http://www.pavementsucks.com/tech/fanclutch.php

MT

Glad that's all figured out! I, of course, had to get the one strange model.

I've never heard of such a thing anywhere else. Of course this makes me wonder, what's special about that particular engine, WP, or seal? Must have been some sort of problem--I can't picture engineers deliberately designing things that way.

The GM parts guy didn't look at me like I'd lost my mind when I asked for them. He actually had two different packages of pellets, one smaller than the other. They must use them in some other application.

I appreciate your taking the time to check into this. And thanks for the pointer to the other forum. I'm just starting to learn about these iron-engined creatures and the more places where I can read and ask questions, the faster I'll learn.

You are welcome.
And thanks for posting the info from the GM repair manual on it.
If the dealer had a good supply of tabs I would think there is some more problems on other engines to.
On a lot race engines a lot of them require stop leak and use stop leak after a engine rebuilt.
Good luck
MT