New Member S/W Ontario Canada, With Questions??

**Old Iron nut** · 03-06-2013, 08:17 PM

Just got a 1998 Chev 3500 Cheyenne 1 ton with a 350 engine. Motor was replaced about 5 years ago with a brand new crate motor from GM. Original motor failed due to leaking intake manifold gasket. The present motor also has the same problem-antifreeze in the crankcase, also attributed to leaking intake manifold gasket. What years did this problem start and when did it end? The local rebuilder advises me that this was a common problem. Does anyone know if this a machining error or poor gasket on the part of GM? Apparently there is a replacement gasket that solves this mess. I don't have the motor out yet and will have to wait for the climate to warm up before I pull the engine. Cheers, Old Iron nut.
PS. Truck has low mileage.

**99'HEARTBEAT** · 03-06-2013, 08:43 PM

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**RayVoy** · 03-07-2013, 04:08 PM

You should be able to fix it without pulling the engine. I had the same problem on a 4.3 and fixed it by removing the intake while still in the truck.

Do a google search on Dexcool antifreeze and leaking intakes, that should answer all questions.

**Skippy** · 03-08-2013, 10:32 PM

Oh yeah. Ray's got the right of it. As soon as I read the magic "5 years" mark, I instantly thought Dexcool.

That stuff needs to replaced every 2 years on the spot. The additive package just isn't sufficient to protect your engine's aluminum parts. Great for cooling, but nasty on gaskets!

**Old Iron nut** · 03-09-2013, 08:33 PM

Skippy. don't know whether or not the engine had Dexcool or not, the problem started about 2-3 years after the new motor was installed. The truck has not been plated for the last 2 years. I don't know if Dexcool is the same as the Cat long life antifreeze but I know the Cat stuff does not have to be changed every two years. There are a few other GM owners with the same problem of leaking intake manifolds. Cheers, Old Iron nut.

**Skippy** · 03-10-2013, 11:22 AM

Originally Posted by Old Iron nut

Skippy. don't know whether or not the engine had Dexcool or not, the problem started about 2-3 years after the new motor was installed. The truck has not been plated for the last 2 years. I don't know if Dexcool is the same as the Cat long life antifreeze but I know the Cat stuff does not have to be changed every two years. There are a few other GM owners with the same problem of leaking intake manifolds. Cheers, Old Iron nut.

http://www.consumeraffairs.com/news0...m_dexcool.html

Dexcool, btw was supposed to last 5 years or 150K miles. Any dexclone antifreeze is likely to have the same corrosive properties. Can I guarantee the intake manifold leak is a direct result of the antifreeze by evaluating a forum post? Absolutely not! LOL

That being said, I'd still take a peak at what the formulation was. And if it's a Dexcool clone, I'd still be changing the stuff every 2 years... It's just not worth a bum engine. Too much evidence that shows Dexcool formulation DOES last 5 years, but the engine in which it's operating DOESN'T. *grin*

-Skippy

**Old Iron nut** · 03-10-2013, 08:46 PM

Many thanks for the reply, Skippy. I have been using the long life Cat antifreeze and Mobil 1 synthetic oil in all my equipment and have not had any problems. I'm hoping to remedy the problems in the 98 Chevy after I tear it down and correct same. Funny, I don't have leaking intakes on my old Cats. Only been working on them for over 40 years. Cheers, Old Iron nut.