[dreamingmuscle]

I have a 98 Oldsmobile Silhouette (Mini Van). with a 3.4 6 cylinder engine.

Anyways it started running rough a couple of weeks ago and the idiot light came on. My son scanned it and it said there was a miss fire on one cylinder. Internet search pointed to a bad spark plug or coil. We continued to drive it since it smoothed out after a couple of miles. So last week it over heats a little because the coolant was low. Added fluid everything was fine. The low coolant didn't concern me because its always lost some coolant. But I could never figure out where even though I've searched the vehicle over many times. Never smelled hot coolant either. So yesterday it didn't want to start for my wife after she came out of the bank. I went and switched vehicles with her and brought it home. Coolant was low again. Hmmm no puddles, no hot coolant smell Checked the oil everything looked fine color and level.

Then I pulled the oil filler cap, Crap a creamed coffee colored film was all over it.
So I'm thinking head casket. But I do remember something about the intake caskets going bad fairly regular on these engines.

Anyways your opinions are appreciated.

If it is the intake casket do I still need to pull the engine to fix it? It seems every other repair to requires that the motor mounts be removed and the engine leaned back. It has 167k miles on it and this is the first real problem it's giving us.

Glen

[John V.]

Sounds a little like the 4.3L in my '97 Safari.

I was burning coolant for some years. Never saw an external leak. Coolant level would get low, I would just keep a close eye on it. Never any evidence in the oil.

Then one oil change, found LOTS of coolant in the oil. It had obviously gotten a lot worse.

Figured it was time to get serious about it and had the Intake Manifold gaskets replaced. Problem solved. Don't recall the date and mileage at the moment, as a guess '04 and 130K miles.

All was good until late '07. My son was driving on the Interstate doing about 75 when it spun multiple rod and main bearings. No warning, no oil smoke, no strange noises, just suddenly let go. 175K on the odo.

I had a rebuilt engine put together and installed (original block and crank were history) which now has 18K miles on it.

No explanation for why the engine blew when it did. The engine was well maintained as far as oil changes every 3-4K. I've owned it from new.

I have always thought that letting that internal coolant leak go on for a few years probably shortened the life of the bearings and eventually caused the failure. Maybe had no impact, but I still wish I had not ignored the coolant loss for as long as I did.

My guess is you have had a similar intake gasket leak, not a head gasket. Lot of folks will say it is the Dexcool coolant. I don't buy that. I point to the intake gasket design, prone to getting brittle.

Safari is a pain, access thru the engine cover. I took mine to a shop, think I probably paid about $500 for the work. I am not familiar with the Silhouette engine access or your engine.

I no longer really "need" the Safari, keep it to haul stuff (like mulch!) and a good spare when another car is being serviced. But if I was in your shoes, I probably would advise trading it in rather than dumping money into it. It'll probably cost more than it's worth to have the intake gaskets replaced unless you have the ability to DIY. And it will still be old when you're done. And I'd hate for you to blow an engine like I did and then it's worth nothing.

It's a tough call and your own circumstances will dictate. We went thru the debate when the engine blew. I wound up agreeing to dump about $3K into the Safari at that time thinking I'd have a better vehicle than if I bought any other $3K used car. But hidden costs for the bad block & crank cores and a trans repair I did on my own drove the total to $4K and then spent another $800 or so when the fuel pump quit on the road returning from dropping my son off at college last summer and another $150 to weld in a new Cat when that started rattling (probably damaged when the engine severely overheated when the bearings spun, a baffle came loose, otherwise there wasn't a thing wrong with it). $5K just wasn't justifiable. And at 16-17 mpg and a pretty high insurance premium, I'd probably spend less if I rented something when I need to haul stuff.

If the Silhouette is in excellent shape otherwise, get the intake gaskets replaced and cross your fingers.

But I'm guessing it has plenty of "issues" at this point and with the mileage you have on it, might be a good time to think about a new one, or a lot newer used one.

Hope it works out.

[Lightfoot]

If you are adept at doing minor engine work yourself, you may even try pulling the oil pan and inspecting the rod bearing furthest from the pump. If it looks good, then it's probably worth having the intake gaskets replaced. It depends how difficult to pull the pan.
The intake job should be routine for a shop that does alot of that work.
I would flush the oil system out real good before the tear down. Use 3/5 concentrate of ATF or something similar. Let it idle just long enough to reach operating temp, then let it cool completely, then repeat.
Myself, I wouldn't be afraid to drive it from cold to O/T, but that's not for the faint of heart.

[dreamingmuscle]

John V

The vehicle is in pretty good shape. The interior has no sagging seat cusions stains or tears. The body does have some bruises but nothing major. The only thing it really needs is new head and fog lights since these have faded over.

I wouldn't have hesitated to drive my family to Oklahoma in it this summer. Like I said very dependable vehicle until now.

Glen

[Lemans64]

Yes these are real bad for leaking coolant at the intake gasket, most times they leak internally and the coolant mixes with the oil quite well so it is hard to detect until it starts making ticking sounds from the lifters. The coolant will make the oil sticky and cause the lifters to stick causing noise. the intake gaskets can be done with motor in van, BUT it will make it much easier if u lower the front bolts on the cradle and drop cradle, CAUTION, don't go to far as the steering shaft will come apart. Also watch the abs wires to front hubs, as u lower the cradle the wires will pull and can be pulled apart between cradle and strut towers and or engine wiring harness. I beleive it is around 6-8 hours labour to have done at a repair shop.

[bradkline]

I had the exact same problem with my '98 Bonneville. I kept running through DexCool since it mysteriously disappearing over time. I could detect a faint smell of coolant from time to time and then it got worse and at one point drained the coolant tank within one week. Took it to my favorite mechanic who replaced the plastic intake and sure enough on the old one heat over time had melted a hole in it. Its replacement one had a different (improved?) design that seemed to correct some of the problems of the original.

I don't lose a drop of coolant now and drove it this summer from York PA to POCI convention in Dayton and it didn't miss a beat despite hot temperatures and high speeds.

Plastic may be fine in some configurations but it doesn't belong on an intake manifold on the top of the engine. Some of these new ideas just aren't that great...........

Brad Kline