3800 engine hydro-locked

Olds Intrigue 1998, 165K, wouldn't crank, removed plugs and put dry cardboard in front of plug holes, then cranked it and it blasted coolant out of both banks, in what appeared to be mostly on the passenger side
holes. Car ran perfectly normal when shut off last time it was driven (the previous night). It has had an issue with losing coolant and needing to be topped up periodically -- but never got very low. The oil has never appeared have any milky looking substance in it, usually associtated with coolant in the oil. 1.) Since it blew coolant out of plug holes on BOTH banks, I presume this pretty much eliminates the likelihood of it being head gasket issue -- and, rather, this points to the intake manifold issue these are known for -- correct?
2.) What is the usual protocol for dealing with this, e.g. a gasket replacement kit, or does the actual plastic manifold need to be replaced as well?
3.) Since this issue with these engines is well known, does anyone have any advice, links, etc. for someone dealing with one of these for the first time -- such as any peripherals to upgrade or be mindful of?
4.) What would you say is the best name brand to replace gaskets, etc. with -- or ones to stay away from?
5.) Did the engine experiencing hydro lock condition likely do any additional harm to it, or can it simply have the cause addressed and be good to go indefinitely? TIA
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On Thu, 8 Jul 2010 16:41:12 -0700, dog snipped-for-privacy@msn.com (dog arms) wrote:

1. You need to do the LIM gasket. Only use the aluminum framed gasket. I got mine at GM, about 75 bucks. 2. You need to replace the plastic upper plenum. I got a new Dorman kit at Amazon for about 60 bucks.
Can't remember if new injector o-rings came with the kit or I bought them separately. Blue RTV for the valley gaps, locktite for the manifold bolts. All this info came from http://www.bonnevilleforum.com Applies to your engine too. You'll find the right torque specs there too. The shop manual is wrong, We did my sons before it leaked, after reading about the problem. Think it had about 80k miles. The stock plenum looked okay when we removed it, but the LIM looked ready to fail. Some guys on the Bonneville forum had hydro lock and needed a new engine, others didn't. The important part about that is catching it before the coolant has damaged the bearings. Good luck to you. Think there's instructions there about how some flushed the coolant out with oil and were good to go. Depending on your skill level and speed, it's about a 4 hour job. Won't hurt to take your time and give it a full Saturday. Pretty straightforward. Other than the parts I mentioned, it's a good time to change the idler arm if it's flaky.
--Vic
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That car doesn't have an idler arm.
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wrote:

In my limited vocabulary, an idler arm is part of the steering/suspension.
A tensioner is something else and maybe this is what he meant.
We had a Buick LeSabre of this year model and engine, and it had a tensioner built onto an aluminum coolant bypass (for lack of a better way to describe it). It failed on the highway with less than 80K miles on the car. The car was all but impossible to drive to the next offramp where there was a GM dealership.
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Yep, my mistake. Tensioner. My son's had a slight "hitch" in it, so he replaced it while it was easy to get at. That coolant elbow attaches to that assembly to get the coolant to the other side. Always struck me as a bad design, since a lot of them develop leaks. His original already had a slight leak. And be careful you put the PCV o-rings on correctly when you stick it in the plenum (-: Here's a thread about that, and says the LIM bolt torque is 132 inch pounds. But verify that on the Bonneville forum. http://groups.google.com/group/rec.autos.tech/browse_thread/thread/31fc97f8c236690b/4e732b4cc4ade70f?hl=en&q=salute+to+the+pros+vic+bonneville
--Vic
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dog snipped-for-privacy@msn.com (dog arms) wrote:

Very likely correct.

You need to replace the upper intake plenum (plastic), you should also replace the lower intake manifold gaskets.

Use either the FelPro problem solver gasket set (MS 980014T) or the upgraded GM gaskets. The gasket you want will have a metal skeleton instead of the original design plastic.

Avoid the Victor-Reinz gaskets, they're identical to the ones that fail. Upper plenum either Dorman or GM, you'll probably find better pricing on the Dorman. Also, there is a plastic coolant elbow on the passenger end of the lower intake, it WILL break on disassembly, use the GM replacement only, the Dorman copy is crap and will fail in less than 6 months.

Had this happened at highway speed, you'd probably be looking at replacing the engine, worst I've seen when the failure is like yours (cranking hydrolock) is a snapped nose on the starter motor.
O2 sensor(s) are probably contaminated.
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