3.4 V6 Question... and favor!

Guys,

I drove my wife's Olds Silohuette mini van w/3.4V6 the other day to get it inspected. While out and about I noticed the heater wasn't blowing and the temp guage bounced around a bit and came close to overheating at a stop light. I suspected a bad thermostat. It's a 2002 with 107K. The dealer looked at it and said the manifold gasket is leaking and the coolant low, causing the overheating problem. He wants $900 to replace the intake manifold gasket! uggg. I'm not going to have him do it 'cause #1, I'm cheap... #2, I don't have the bux #3, I can wrench pretty good myself. I just hate working on the van cause the engine is tucked back in there.

Here's the favor. Could anyone scan or fax me the pages from an manual that shows the steps for a intake manifold replacement on a Chevy 3.4 V6? I would be REALLY greatful!

Man, John.....there for a minute I thought you were coming over to the dark side and converting either your MGB or you Frogeye!

:eyepop:

PM sent

Thanks Larry!

While changing the intake gasket can be a big job, for the uninitiated, it is not impossible and only requires some metric hand tools. Before you commit to it though, try this instead. Disconnect battery ground, remove both front engine steady mounts, remove the upper intake manifold and use a cheap ratchet tie-down strap to pull the engine as far forward as you can get it. Don't fret, this is all easy stuff, but pay attention to clearances so you do not bind or break anything. It's not likely you will but just play it safe. Now take a wrench or socket, whichever works best, and tighten down the lower intake manifold.
I would bet that you will find many of the bolts to be very loose. Screw the manual on the tightening torque and just snug them up real well. This does not mean as hard as you can manage to reef it! Use a bit of judicious restraint. Put it back together.

If you have enough water in the oil to make it all foamy then you should change the oil before proceeding further. If you let the rig set overnight any free water will drain to the bottom of the pan and you can pull the plug only enough to let the water out, stop when you see unpolluted oil start to drain. If it is not too bad then drain and flush the rad and refill only with water.
Now take it out for a drive and stop every few miles to see if it is still heating up and foaming the oil. If not then keep driving until all of the moisture is gone. It may not take too long as the heat and crankcase vacuum will make short evacuation of what water remains. If you still have a problem, but much lessened, then you can try a good quality Block Seal compound found at many auto parts stores. Follow the directions closely and you will be surprised at the results you get.

Of course the direction you take is totally up to you, this is what I would do and the cost of it is way less than what the gasket change would be. What do you have to loose?

Here is a pic of what a worst scenario would look like and it did seal effectively, with out being tightened, It did eventually fail again but I drove it many thousands of miles before it did. Had I known to tighten the manifold too I doubt if it would have failed at all.

If you try this, and are successful, don't forget to add anti-freeze for the winter!

Brad

LIM gasket failure is the biggest problem with the 60V6 engine and if not taken care of properly can destroy an engine. The factory gaskets are made of plastic with silicone inserts and crack from age, heat, pressure and improper torquing. Felpro makes an excellent set of replacements called "Problem Solver" gaskets. They are made from aluminum and silicone and will not crack like the stock gaskets. The stock gaskets will break at some point causing a coolant leak. Where the leak goes depends on which area of the gasket breaks first. You can see in the pic above that the gasket is broken on both sides of the coolant port.

Simply tightening the bolts a little more may buy you a few more miles but only causes you to have to work on it twice, delays the inevitable and risks mixing coolant with the oil which can completely destroy the engine. I have yet to hear of a failure with the "Problem Solver" gaskets. In my opinion, do the job right with good gaskets and you won't have to worry about it again.

I do agree with most of what Marc writes, what I was doing was giving John a low cost alternative to keep his car on the road for the season. I don't care how high quality of gasket you use, if the manifold is loose it will leak.Yes the 3.4 has intake gasket issues but if GM would retorque them as part of its service/warranty program most of these issue would not be so prevalent. Changing out the LIM gasket is not that big a deal for the experienced but how many home mechanics have the requisite tools and expertise to effect a satisfactory, long term, repair? He only has 107K on his engine and the leak is in the beginning stages so I think he could get many many more K miles out of it by following what I have outlined. Sure you can knock out the lower end by driving too much with contaminated oil but most of that occurs to the folks that ignore the issue and continue on as if nothing were wrong. I got my wifes Venture to 183K, but when it again started to leak I swapped a new engine. The old one was still not using oil between changes but I deemed it prudent to renew it since my wife drives a lot of long distance. I got a certified 13K engine ( It was a deal I could not pass up, so good that I bought two of them with the same milage, possibly to put into one of my MGBs) and installed it, but not before I went over the engine and retightened everything. Guess what was the only thing loose? Yep, the LIM, snugged it up and no problems for the past 23K.

When I tore down the old engine it had very little cylinder wear, great looking valves and all of the crank bearings looked as if they could go another 183K. The timing chain was loose and one lobe of the roller cam was showing some wear. No other wear issues that I could see.

Brad

Let me add something. :)

Van's are quite different than the MGB V6 conversion- the van is a Bear to work on but its easy in the MGB!

That said, my wife's 2000 Venture (same as the Olds Silo) engine was problematic and around the 107K mark as well. I dropped the engine because it was just terrible in appearance. It looked like the oil had never been changed- or always changed with Pennzoil!

We removed it and replaced it with one with around 60,000 miles or less on it. I didn't retighten the LIM gasket and knew I should have. It's still running but.....

-BMC.