Short Version: '97 Lesabre engine is losing coolant, smoking white out of tailpipe, and won't turn over at all to start, then it finally turns over and starts but gets rough and stalls.

I'm hoping it'* only the manifold gaskets leaking but have I done more damage? If I can't fix it myself then it'* headed for a scrap yard.

Long version:

1. Buick '97, 3800 II, 49K mi. Hadn't been driven in 2 months, ran fine with no OBD2 codes at that point.

2. Started up fine, left her idling in the driveway for 1/2 hr to charge the battery and get fluids moving about. Saw a check engine light when I turned it off but it had been idling fine.

3. Tried to start it a week later. Heard starter click but engine wouldn't turn. I thought maybe bad battery or starter so proceeded to jump start it. Engine still won't crank. I wait a few minutes to get jump start juice into battery and then keep trying. About 10 tries later it starts but runs rough, white smoke pouring out of tailpipe.

4. I shut it off, pulled OBDII codes with only one code indicating multiple misfires - think it was code P0300.

5. Checked radiator. Could not see any fluid in it. Filled it most of the way with water (for the time being). Started engine, took 3-4 tries, ran okay for ~ 10 second then degraded to really rough and stalled out. Exhaust smoking white again.

I am assuming a coolant leak but none is in the oil and no sign of it leaking elsewhere.

Do you think the engine was hydrolocked _BEFORE_ started, after sitting a week, causing the hard starting and if so, how likely is it that it is now damaged?

Is it possible the thermostat was stuck when it was idling for 30 minutes a week ago and overheated, warped or cracked something, or shouldn't that have triggered an OBD2 overheat code or not?

I've done a little research about the manifold leak issues with these engines, have already bought a (metal) Felpro lower intake manifold gasket kit, thermostat, coolant temp sensor, upper intake plenum kit, coolant elbows.

Should I just swap all this stuff in and see if that fixes it, or is there something else I should check first, or during the swapping? Checking for warp-age is probably beyond my capability unless visually obvious using a straight edge.

I had thought about cylinder compression testing but I don't have a gauge, plus wanted to avoid pulling plugs "IF" it'* avoidable as I just changed them a few months ago (ran fine after that). If I have a cylinder full of coolant would that FUBAR a loaner compression gauge?

"IF" the engine seems to crank can I avoid pulling the plugs? If it doesn't seem to want to crank what is the risk of doing damage, if it wasn't done already, of trying to crank again for ~ 10 tries as I did previously? I mean after swapping the gaskets and plenum.

I'm trying to decide if I should just swap the parts in or if it'* likely to be wasted effort or prudent to check or do something else first... at least they're dry gaskets, can I take it all back apart if there'* still a problem and reuse them or are they shot once compressed once and engine does or doesn't run for only a few seconds?

Yes you hydrolocked your engine. Did you damage it? Who knows. Remove ALL of the plugs, and do a compression test of each cylinder. Your battery must be connected to an external power source for this test. Otherwise a half dead battery will cause the engine to turn over slowly and skew the results. Don't do anything else until this is done. Otherwise, you will waste money if your just going to scrap it.

What seemed strange was that it was running fine last time, then wouldn't turn over at all the next time I went to start it a week later.

I had wondered if it wasn't hydrolocked but instead a piston(*) had rusted in place or something.

I've never done a compression test so while I had a basic idea of what'* involved, I may be assuming too much. Doing a compression test in a case like this, should I pull all spark plugs first and leave them out? If so do I then still need to disconnect the ignition coil pack or pull the fuel pump relay or fuse?

Would it be reasonable to skip the test on cylinders where the spark plug looks good and only do it on those that look wrong? I suppose I can't though, need to do at least one working properly for comparison purposes?

Have to agree with Mike, sounds like you have a hydrolocked 3800, pull the plugs, but before worrying about a compression check, do a little observation first. Maybe fix a mirror with a good light source so you can see the plug holes on the bank next to the firewall, front plug holes will be easy enough to watch while you have someone crank it over. Any coolant coming out of a plug hole and you can skip the compression test and decide whether to fix or scrap. Old car but low miles so might very well be worth fixing.

2004 Bonne SLE
1971 Chevelle SS

You can hydrolock a 3800 without damaging it. If the compression test comes out fine, then proceed with replacing all intake gaskets and coolant elbows.

Well I'm sure there'* coolant getting into one or more cylinders because it has to be in order to be burning it out the exhaust.

Should I be pulling one plug out at a time, then cranking to look for coolant, then moving on to do the next plug?

What does seeing coolant coming out of a plug hole tell me about what to do next? Wouldn't that also be a symptom of a problem that only needs the upper and lower manifold gaskets fixed, or are you saying seeing coolant means a positive sign it is getting enough vacuum to suck in coolant or pressure to push it out so it'* not likely to need more fixed than the UIM/LIM gaskets?

Upon looking again I see no oil leaks but do see a slight coolant leak which seems to be coming out the manifold plenum gasket area near the distributor... but nowhere near enough to account for the amount of coolant lost and it'* still coming out the exhaust.

Stop speculating. It doesn't matter if its one or three or six. Remove ALL spark plugs. Crank over and see if its blowing coolant out. I already know the answer. Unable to crank over, no coolant in the radiator and misfire codes point to one thing. Its sucking coolant.

BUT what I want you to do before doing anything else, is to do a compression check on each cylinder.

So if the compression check doesn't come out good then it'* a *sure* sign it needs more than the gaskets?

Since I don't have a compression gauge and hate to keep throwing money at this until I know if it'* within the budget to salvage the vehicle, I had considered the Autozone loaner-tool compression gauge but the only 3 reviews on it all state similar, that it has trouble reading pressure (above 90PSI).
OEM/Compression Tester Gauge Set 27138 - Read 3 Reviews on OEM #27138

Is hydrolock damage likely to cause a pressure reading below 90 PSI?

lol, I may be asking too many questions in an attempt to stall emptying out the garage to put the vehicle in there and take it apart for a few (currently) rainy days but need to get started ASAP.

Oops, meant small leak near the ALTERNATOR. I guess I'll just break down and get the Autozone loaner compression gauge then if it'* inconclusive I'll go from there.