Preventing 3100 SFI engine failure?

[ItsVince725]

The 3100 SFI in my Buick Skylark seems to be notorious for suffering engine failure, especially hydrolock induced by blown head gaskets. The water pump also seems to be a weak link, as my "grandma car" Buick needs it replaced.

So what I'm asking is, what can I do to keep my 3100 trucking along as long as possible?

[robertisaar]

head gaskets aren't as common as LIM gasket failure, unless you significantly overheat it. that gasket is crap from the factory, there is a good Fel-Pro set made, i know Ben has them listed via WOT-Tech.

water pumps.... i guess kinda common, but it's also pretty much a 10 minute job, you spend more time bleeding the air out than you do changing them. they're also really cheap.

the oil pump drive seal is also pretty common to go, leaks a BUNCH of oil, usually misdiagnosed too. good to do when changing the LIM gaskets, takes another couple minutes to get at.

otherwise, change the oil regularly(~7500 miles or less), monitor it's level/color at least once a month, don't use crap filters and you're pretty much going to have to scrap a car due to structural rust or killing the transmission before the engine is the reason to get rid of it.

[ItsVince725]

head gaskets aren't as common as LIM gasket failure, unless you significantly overheat it. that gasket is crap from the factory, there is a good Fel-Pro set made, i know Ben has them listed via WOT-Tech.

water pumps.... i guess kinda common, but it's also pretty much a 10 minute job, you spend more time bleeding the air out than you do changing them. they're also really cheap.

the oil pump drive seal is also pretty common to go, leaks a BUNCH of oil, usually misdiagnosed too. good to do when changing the LIM gaskets, takes another couple minutes to get at.

otherwise, change the oil regularly(~7500 miles or less), monitor it's level/color at least once a month, don't use crap filters and you're pretty much going to have to scrap a car due to structural rust or killing the transmission before the engine is the reason to get rid of it.

This might make me sound like an idiot, but what's a LIM gasket?

[robertisaar]

we all gotta start somewhere.

lower intake manifold. specifically, the gasket that goes between the lower intake manifold and the heads.

[pocket-rocket]

The reman water pumps with the stamped steel impeller don't move as much coolant as the new ones with cast impellers do. It's not so important on stock 3x00 engines, but on modified 3x00s or the DOHC (stock or modded) it won't keep up.

Also, if you haven't done so already, once done changing the pump flush out any dexcool and change it over to standard green coolant. Your gaskets will thank you.

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[bob442]

I'm finding my car running cooler on the stamped steel prop pump, just changed from the cast version, also thinking it won't cool as much, but I was in a pinch and it was avalible...

[pocket-rocket]

Odd. Over the years everyone else has found the cast to cool better. Maybe there is a different stamped steel one on the market that you bought that has more than 7-8 fins.

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[ItsVince725]

So you can flush out the Dexcool and switch to green coolant without hurting the engine? Good to know, I've heard that Dexcool SUCKS.

[pocket-rocket]

Yes you can. I highly recommend it. Dexcool is know to attack gaskets in bimetallic (aluminum heads and iron block ring a bell?) when left in service for too long. I for one wouldn't wait out the manufacturer suggested 100k miles... I personally buy nothing but the green.

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[ItsVince725]

Well I feel silly, I forgot that Dexcool is red.

My car has green coolant, so it's already been wisely un-Dexcool'd and filled with the good old green stuff.

[TGP37]

Hydrolock induced blown head gaskets? Are you leaking coolant into the combustion chamber?

The number 1 killer of head gaskets is over heating the engine. I would check everything regarding the coolant system. Also replace the fuel filter (clogging filters can cause overheating), if not done recently. Any air leaks in the intake past the MAF, if you have a MAF sensor, can lead to overheating (running lean). Failing thermostat may also be an issue now.

If your oil looks like muddy water, or your oil fill cap under side looks like it was splattered with mayonnaise, you have a LIM leak as well.

[ItsVince725]

Hydrolock induced blown head gaskets? Are you leaking coolant into the combustion chamber?

The number 1 killer of head gaskets is over heating the engine. I would check everything regarding the coolant system. Also replace the fuel filter (clogging filters can cause overheating), if not done recently. Any air leaks in the intake past the MAF, if you have a MAF sensor, can lead to overheating (running lean). Failing thermostat may also be an issue now.

If your oil looks like muddy water, or your oil fill cap under side looks like it was splattered with mayonnaise, you have a LIM leak as well.

This was my mother's car, not mine. But it was leaking coolant that didn't seem to be going anywhere, and then the engine seized and there was crystallized glycol under the valve covers. I dunno if that's hydrolock or not.

[pocket-rocket]

If I had to guess without seeing the teardown I would say it wad a LIM gasket that never got found and the constant concentration of coolant in the oil killed the bearings causing it to seize. I caught a couple of them before it went sour.

Coolant in the oil attacks the bearing material and damages it.

Luckily the one didn't wear so fast that we didn't catch the low oil pressure warning. Yes, all engine bearings and the cam had to be changed, but that engine is still on the road trouble free 7 years later.

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[TGP37]

If I had to guess without seeing the teardown I would say it wad a LIM gasket that never got found and the constant concentration of coolant in the oil killed the bearings causing it to seize. I caught a couple of them before it went sour.

Coolant in the oil attacks the bearing material and damages it.

Luckily the one didn't wear so fast that we didn't catch the low oil pressure warning. Yes, all engine bearings and the cam had to be changed, but that engine is still on the road trouble free 7 years later.

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Plus, the coolants water content is usually boiled off in the oil, leaving behind some nasty particles that scratch bearings/parts.

If coolant was added over time, allowing these particles to collect over time, all the bearings are trashed.