Coolant smell

poorboy · November 28, 2005

So my 2002 z71 with 56000 miles was starting to get that coolant smell we all remember from our first cars in high school. You remember, the 67 camaro that had coolant driping from it every friday night as you drove around town.

Well this aint no $1000 car It a $30,000 truck that has for the most part been pampered it's whole life.

So, has anybody else had this issue? It's a 5.3 and it is leaking from around the oil pan gasket on the drivers side front. It is coating the top of the skid plate and running through the holes. It is bright red and doesnt' have any oil in it. Parker overnight it will leave a 1"x3" spot of coolant.

I checked the water pump, it looks dry. I checked around the intake, it looks dry. I checked the hoses, they look dry.

So what do you think I'm up against???

Norseman · November 28, 2005

It is your water pump gasket. Replace with Fel-Pro. You will need 2 of them.

This will fix your problem!

poorboy · November 28, 2005

ya, think so? How bad of a job is it. Is this a common problem? Any chance GM will take care of it out of warranty?

Norseman · November 28, 2005

I wouldn't say it's a real common problem but, that is what my problem turned out to be. You can always try to get GM to cover it. I would not waste my time. It is a easy and inexpensive job. It only took me about 40 min to do start to finish. Just use FEL-PRO!!! Don't go cheep! I can talk you through the job if you need it.

poorboy · November 28, 2005

Thanks, I let you know if and when I decide to go for it. Thanks again.

flatlander · November 28, 2005

So my 2002 z71 with 56000 miles was starting to get that coolant smell we all remember from our first cars in high school. You remember, the 67 camaro that had coolant driping from it every friday night as you drove around town.

Well this aint no $1000 car It a $30,000 truck that has for the most part been pampered it's whole life.

So, has anybody else had this issue? It's a 5.3 and it is leaking from around the oil pan gasket on the drivers side front. It is coating the top of the skid plate and running through the holes. It is bright red and doesnt' have any oil in it. Parker overnight it will leave a 1"x3" spot of coolant.

I checked the water pump, it looks dry. I checked around the intake, it looks dry. I checked the hoses, they look dry.

So what do you think I'm up against???

<{POST_SNAPBACK}>

This reply may be late but I have experienced the identical problem you described and the 4.8 is now at Chevy getting the $420 water pump job. Because the fan and air blow the coolant all over the place it is hard to tell exactly where the leak is coming from. I too thought the leak was coming from the left, front corner of the engine block but there are so many things blocking the view that it is hard to tell. Had expected the water pump to go longer than 50,000 miles but at least it now gets the Goodwrench warranty if it ever leaks again.

Norseman · November 28, 2005

It's not usually the water pump that is the problem. It is the WP gasket.

asepgrad98 · November 28, 2005

If are paying someone to take the WP off to change a gasket at 50k miles might as well change WP as well.

n5xl · November 29, 2005

Pretty common problem. I've run into several people on other forums that have had or currently have their water pump gaskets leaking. The water pump gasket is a metal plate with two red rubber o-rings fused to the metal. Over time, the o-ring separates from the metal gasket material and thats when the leak starts. On my 01 SIlverado 4wd, I was able to see the actual leak by getting under the truck and removing the front skid plate. If you look up through the harmonic balancer, you will be able to see the underside of the waterpump on the passenger side, which seems to be the most common place they leak. After removal of the gaskets, you will see how dirt and grime gets between the rubber and the metal gasket material. The black area on this o-ring was the problem area on mine. What isn't obvious in the picture is how little force it took to remove the o-rings from where they are attached to the metal. It was supposed to be solidly fused to the metal.

Avoid the problem in the future and get the paper Fel-pro gaskets. You can get them at virtually any parts store. Clean the block surfaces with a gasket scraper and clean up the water pump. RTV the new gaskets to the pump and put a thin coating of RTV on the block.

Doing the water pump is a pretty easy job on the 5.3...can't speak to the other engines.

Norseman · November 29, 2005

Been there done that. I originally tried the paper and a year later it started leaking again. I'd go with the aluminum ones. Those are great pic's though. The metal Fel-Pro's are not like the stock. The rubber is wraped around the aluminum.

n5xl · November 29, 2005

Been there done that. I originally tried the paper and a year later it started leaking again. I'd go with the aluminum ones. Those are great pic's though. The metal Fel-Pro's are not like the stock. The rubber is wraped around the aluminum.

<{POST_SNAPBACK}>

I'm surprised at that. "Paper" gasketing material has been used for years, and still is quite successfully being used on waterpumps. I can't recall seeing a properly installed water pump leak at the gaskets before this metal/oring design came around. I'll be the first to tell you "you told me so" a year from now if it happens though. I'll will take a closer look at the aluminum one you mentioned, so thanks for the heads up.

Since you've done a couple of these, I'd be interested in hearing your thoughts as to the reason these base gaskets leak. I thought about taking this off forum and just sending you email, but maybe someone else has some insight into this, so Ill leave my ramblings here. Let me start off by saying I am not a trained mechanic. I have been "wrenching" since I was in Jr. high, and now that I am pushing 40, auto repair to me is more about doing a quality job the first time....you know what I am saying. I think we've all been there before. With that out of the way....

I'm convinced that the oring is much too easily displaced from its sealing metal surface which is what causes the leak. What I have been wresting with is what causes the orings to become unfused and displaced in the first place. A couple of theorys I have are...

1. "Shrink/swell" of the rubber over hundreds of heat cycles that causes the orings to finally separate from the base metal gasket.

2. Antifreeze ever so slightly effects the oring material, causing it to shrink or swell away from the gasket over time.

3. Dirt and debris builds up on the engine block face, and that pushs the oring away from the aluminum base metal gasket.

4. Dissimilar metals in direct contact with each other in the presence of an electrolyte...antifreeze.

The 5.3 I have is the typical iron block design. (.....which as a tangent to this conversation, it would be really interesting to know the water pump leak rate on aluminum block GM engines and if they suffer this same base gasket leak....). When I took off the water pump, the gaskets were attached to the water pump and came off with it. After removing the gaskets, The aluminum gasket material was spot free and clean on the water pump side, as was the oring. The problem I had on mine was on the block side of the gasket. Dirt and debris had built up enough to displace the oring from the metal gasket. The oring on the block side was black and rough in several areas and was obviously not sealing to the block. On closer inspection, the black "dirt" had worked its way into the area where the oring is supposed to be fused to the aluminum base gasket. I have seen a severe case of this where th oring had unfused and was actually partially pushed into the coolant passage by the dirt. It looks like black dirt, but its hard to tell. It could actually be corrosion of some type that is building up over time. which made me think of number 4, but it could actually be number 3.

So in the classic "chicken and egg" question....which comes first? Does the oring unfuse first and allow coolant to escape to the flange area and cause corrosion to build up, or is it the dirt and corrosion that build up first that cause the o-ring to unfuse. Since I don't know the answer to the question, I've decided to try to avoid several potential failure modes I see by going with conventional gaskets. My thinking is that number 1 and number 2 are avoided by not using rubber orings and using conventional gaskets. Number 3 and 4 are avoided by the same AS LONG AS you RTV both side of the gasket. I don't normally RTV both sides of a waterpump gasket, but in this application, I think it may be necessary. My bet is RTV on the block side will seal off the iron surface and prevent corrosion. If my water pump base gaskets leak now, then its not due to any of the above, but due to a poor design by GM, either by too little clamping force (not enough bolts) or too little sealing area, or both.

poorboy · November 29, 2005

Thanks for the information. This is a really good topic. Sure beats the heck out of "What kind of shocks should I get?" and "will 285's fit on a stock NBS without a lift?"

Just kidding around. Thanks a buch for this info.

Norseman · November 29, 2005

Reason for using the aluminum gasket.

The molded rubber bead actually does the sealing, the aluminum carrier keeps the gasket in place and assures uniform pressure along the sealing surfaces. In fact, when properly installed, this gasket helps prevent overtorqueing. The aluminum is molded to the exact thickness needed for this application. As a result, the aluminim gasket performs in the same way as the OE gasket but, it does not exibit the same problem with oring seperation due to better design of oring material.

I hope this helps.

M1008 · December 24, 2005

Reason for using the aluminum gasket.

Norseman - Would you post the Fel-Pro part number for the aluminum gaskets? The part guys I called that stock Fel-Pro supposedly do not find another Fel-Pro number other than the paper "35635" gaskets.

az'03Silverado · December 25, 2005

My WP started leaking at around 5000 miles. The dealer had it fixed under warranty in about 1hr. I'm thinking they probably just removed the belt and loosened the WP to slide in some new gaskets. No problems yet and I'm at 33,000 miles now. Although, if it goes again I'll probably have to do the job myself which will be about all day with my luck.