oil in coolant?

We noticed what i can only describe as sludge in our overflow tank and on radiator cap on 1999 chevy venture. the "sludge" is brown in color and
clumpy. had the coolant system flushed around 120,000 miles. Now at a little over 130,000 miles, "sludge" is back. im kinda thinking maybe oil or trans fluid is leaking into coolant. anyone else ever had this problem or any thoughts on fixing it? i forgot to mention van has 4.3l engine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you were loosing trans fluid could be the radiator/trans cooler. The engine must be a 3.4 not 4.3, anyway if the sludge is only in the tank and on the cap, this may be reisdue form the the flush and just clean what you see and repalce the cap, if the radiator is blocked up this is a problelm, was Dexcool reused or green put in? Sludging can be cause by degradation and contamination of the Dex, if left in too long or the cap doesn't seal properly.

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Does it have the red colored Dex-Cool antifreeze in it? If it's not been changed before 120,000 miles you may be experiencing issues from that. Even after flushing it at 120,000 miles if you didn't clean the system with a chemical flush you could still have remnants of the fubarred Dex-Cool in there.
Does the transmission or motor loose oil / fluid?
Brian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Brown and clumpy sounds more like sealer tablets were added to extend the time so that the leaking intake manifold gaskets wouldn't be discovered until the vehicle was out of warranty.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 16 Dec 2006 16:30:00 GMT, aarcuda69062

THis may have some merit. Given engine and age, GM had a lot of problems with intake gaskets and if it has never been changed someone may have put sealer in it. I have had the intake gaskets replaced twice on my 2000 K3500 with a Vortec 350 free of charge in just over 38K miles total vehicle mileage. The last one a month ago and the time before that almost 2 years ago. The latest change used a revised gasket gasket and they told me that it should not cause any more problems but they would make it right if it did. Some 4.3's were bad about leaking and saw a gasket revision sometime before the 5.7's was. . ----------------- TheSnoMan.com
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
aarcuda69062 wrote:

No way! We "love" those intake manifold gasket jobs. Even under warranty time, we make tons of money. I suppose there may be some dealers that shy away from the job, but in our shop, intake gaskets and head gasket jobs on these engines are considered "pure gravy".
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Even at factory labor times?

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Not after GM cuts the labor time because of his last post. (nyuk-nyuk)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
aarcuda69062 wrote:

They've got better things to do then browse these forums. Plus, they already spy on us anyways. The labour times on intake gaskets has already been cut back....GM sees the averages thru all the warranty work orders that are submitted anyway.
Which is why I keep telling the guys in the shop to leave themselves punched onto the warranty lines.....let em rack up the time on those lines. Meanwhile you can do the cp lines while you are running time on the warranty lines.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Shep wrote:

Oh my goodness...yes! It pays about 4.5 hrs in a Venture van, and it can be done in 2 hrs. We do so many of them that most of us could probably do them by feel.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
shiden_kai or cuda....
how long does it take to replace head gaskets on a 99 tahoe 5.7? Also, do I replace the bolts...or are they reusable?
I'm thinking about doing this one over the holidays. I'm trying to decide whether to try the intake gaskets first...or just dive right into the heads.
I'd really like to R&R the whole engine....but I can't do it until late next year when my new workshop is finished.
Right no there is no evidence of oil in water or water in oil....just coolant dripping all over...even with a 7 lb cap.
skimmer

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
News Skimmer wrote:

Unless you know for certain the head gaskets are leaking, I would not bother with them. If you are just guessing, or want to cover all the bases.....don't. We almost never do head gaskets on those engines. But lots of intake gaskets.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I bought this truck about 2 years ago and have put only about 20k miles on it. (85k to 105k)
After having it about 3 months I noticed it was consuming coolant. So I topped it off and connected my handy dandy pressure tester to it. I tested the engine COLD so that any dripping fluid would not evaporate. It took about 30 minutes of pumping from 10 to 15 lbs to generate a tad bit (like a tear drop) of fluid leaking out the outer side of the passenger side head. It was not much, but it was a leak. I really couldn't generate a leak I could see when the engine was hot, so I let it go and added about a quart of coolant mix every other month.
This summer, my water pump started dripping and by the time I got to it...the pump was leaking pretty good. I replaced the pump and pressure tested the system before I put it all back together and coolant was coming out all over the manifold and dripping everywhere. I've driven it a few times and there is no water in oil or oil in water that I can see. Last weekend I rinsed the engine very well and topped the coolant. I am not driving it. This weekend I'm going to bring it up to temperature and do my best to see if it is just the manifold or if the heads are leaking too. I also have a test bottle from Amsol to send in to test for glycol in the oil.
I would love for you to be right. As I said before, I'd enjoy pulling the engine and re-building it to better than factory...but I can't do it until late next year. I'm hoping it's just the manifold.
In the mean time, I'm driving my short bed regular cab c1500 cheyenne. I bought it new for my wife in May of 93. It has a 4.3 that leaks coolant from the front of the manifold where the intake, block and #1 cylinder all come together. I love GM. These trucks are my fourth and fifth GMs. But I wish they'd figure out how to get the gaskets right. They've only been making that block for >40 years.
Skimmer.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
News Skimmer wrote:

If you change the intake gaskets, you will probably get the new design gaskets. I doubt that you will have any more problems in the forseeable future using these gaskets.
As far as the head gasket leaking, it seems to me that it may have "appeared" to be coming from the gasket when in fact it's been the intake gasket all along. At this point, unless you clean everything off, get a good light and a flexible mirror and it leaks while you pressure test it, you may not see anything.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Are you saying that there was no TSB instructing to put sealer tabs in the cooling system?
Otherwise, agree 100%, pure gravy.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
aarcuda69062 wrote:

Not that I'm aware of. It used to be the standard practice with the Northstar engines, but GM doesn't even recommend it for those engines anymore. We certainly do not put the sealer into the 3.4 engines in any attempt to prolong the life of the intake gasket. We just replace it.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.