3400 GM V6 ('98 Silhouette) Water-n-oil, overheats

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566
Location
Columbus, OH
This is at the word of the previous owner. It's a $300 van so I don't mind doing the LIM but I'm hoping I don't have to pull the heads. Will a regular, pull the plugs and crank it with the fuel pump relay pulled compression check, be enough to pretty much rule out head gasket/cracked head? If just the intake gaskets are leaking (confirmed visually) then there should be no compression loss, right? If I get 130+ on all six cylinders, I don't think I'm pulling the heads. The engine feels strong enough as it is, I don't think it's compromised. Of course a 3/4 mile trip home never going above 30 isn't much of a confirmation...
 
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36,537
Location
ME
For $300 you can drive it to the crusher and get $400. So why not snatch it up? You can tell us all about what fun the rear bank was. Even the alternator looks like a hassle. My silhouette was $300 and all it needed was a fuel injector. Drove it a year and a half. Sold it shortly after the rear air ride compressor literally fell off due to rust.
 
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16,304
Location
N.H, U.S.A.
You should be OK with just the LIM - but more importantly do 2 oil changes - one at 500 miles/1 week and the other at 1000/1 month after doing the lim. While you have it apart, sure check the cold compression - may not show anything worthwhile though.
 
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occupant

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566
Location
Columbus, OH
Yeah I'm in Texas, I don't think rust or corrosion will be an issue. This does have the auto leveling suspension. Also, the junkyard here only offered $125 if driven in. That's why the guy was happy to take my $300. I spent $92 (including tax and core) for a new battery and come to find the bolts were missing off the end of the cables. So $2.50 later I have those and I'm about to head back over and drive it home. Why am I driving it home? I have low hanging trees over the driveway and the whole of the road in front of my house and a tow truck will not fit down our street easily. Also, it's 12 whole blocks away. Love local deals. Love taking road trips more, but with watery oil, it's their house to my garage to drain it and tear it apart. I learned the multiple oil change thing when I did the head gaskets on my '97 Intrepid back in '06. I drained the oil when I did the work and then didn't change it afterwards. Come about 600 miles into it, you bet I saw an oil light at highway speed and shut it down and coasted down a highway offramp and aren't I just a lucky son of a gun, there was a Jiffy Lube RIGHT THERE on the corner. Changed it again at the 1000 mile mark and the girl I sold it to had it for 3 years before selling it to her roommate and at last contact (3/2011) she was still driving it. I'm betting this will be fine. While the oil looks like a caramel frappuchino, soy milk, no whip, triple shot, the coolant is a clean orange with no oily residue and it doesn't bubble when you fire it up with the cap off. All signs point to LIM and heads should be fine. I'm crossing my jumper cables and hoping for the best...
 
Messages
8,576
Location
Ohio
I would run a compression test. You can do it even after you have the intake off. It should catch a bad headgasket, although there can be some coolant leakage even if the compression is good. If you get it tore down to the heads it might be worth it to just take the heads off and replace the headgaskets but that's your call and depends on how long you want to keep the van and its overall condition. This tool might save you some time and trouble. It allows you to remove the rear head's pushrods and you don't have to take off the rear valve cover, alternator and coil pack. http://www.amazon.com/Lisle-48500-Push-Rod-Remover/dp/B000FMNWRQ
 

occupant

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566
Location
Columbus, OH
That tool is also available at RockAuto. Added it to my cart at $12.06, better deal! None of the write-ups or how-tos mention that tool, and if it works I'm happy. But I do want to pull the valve cover only because a new gasket is included and I'm sure it's been about never since it was changed. Van has 204K on it. Engine is a lot cleaner than I expected so it could have been replaced at some point. Wouldn't it suck if someone spent a ton of money to put a low mileage used engine in just to have the LIM's fail? Oh wait, isn't that like every 3100/3400 owner ever? Hahaha...just kidding, GM owners, I'm not bitter or anything, my first 60 degree V6 was an '89 Celebrity sedan for $400 with the 2.8 and overdrive automatic. I wish I could have kept that car but the dealer never supplied a title so I made him buy it back. Back to parts and tool buying, I also put together a cart on Amazon, and the totals are within $3 of each other. The bonus there is that Amazon I have Prime, so I can get free 2-day shipping. If I want it all overnight I could do that for $3.99 per item so for $24 I can have it all Tuesday. But RockAuto stuff always shows up in 2 days in my experience so it's still a wash. Oh wait, I forgot to apply the typical I'm sure I can find it on another forum if there isn't one on here 5% RockAuto discount. Now it's a $9 difference and still worth sticking with RockAuto. Cart contains that Lisle pushrod tool, 1 Fel-Pro gasket set at $65, 1 set of Fel-Pro intake manifold bolts, 1 Gates thermostat, and 2 AC Delco PF47 oil filters. Why AC Delco? They ship from the same location as the other bits and they're black and that's what is on it now, I think. Anyway, I plan to run a compression test. I would love to see six cylinders all evenly matched and not too low. Not sure what the spec is but I can look it up. Can't be too high, I think the LA1 is 9.5:1 so that's around what, 140lbs? 150 maybe? Trying to decide on a good cleaning oil to help dissolve sludge and coolant mixtures from oil passageways and the oil pump. I'm thinking copper bottle Pennzoil High Mileage or possibly, maybe, the Motorcraft Synthetic Blend. 5W30 too thin for this? Weather won't be over 85-90 much and nights are getting down in the 50s-60s. I know it's Texas but it's October. Hey, another oil change question relating to this sort of work, you mentioned and I confirmed the whole 500 and 1000 mile changes, but wouldn't you want a time limit as well, this van will be doing primarily short trips, city driving, drop the boys off at school, take this one to her tennis practice, that one has soccer, honey run to the store and get some ranch dressing packets and a gallon of milk, and all the idling in the world and virtually no highway driving until I'm gosh darn certain that it's not going to leave me stranded and relying on AAA to get me home safely. I can see driving this van 300-500 miles a month tops. Maybe 500 miles or 2 weeks, whichever comes first? Then 1000 miles and 1 month, whichever comes first. Then do a UOA on that change and see how nasty it comes back? Another question. And this is in caps lock for a reason. DO YA DARE ME TO PUT MORE DEX-COOL IN IT?
 
Messages
8,576
Location
Ohio
Sounds like you are a sharp shopper. I only used the Amazon link because it was convenient to link. It wasn't a good price for the tool. I think you should see 140-180 psi compression. I wouldn't hesistate putting Dexcool in because of the gaskets. I don't think it was the issue with the gaskets. You might consider switching to Peak Global, green or G-05. I'd probably go with global if not Dexcool.
 
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1,460
Location
Las Vegas
I bought that Lisle tool when I did a LIM on a Olds Alero 3.4 and it's worth it's weight in gold. With the new bolts (pre-applied locktite, I hope) and Fel Pro problem solver gaskets you should be good to go with Dexcool. I didn't have crow's feet wrenches, and needed a 10mm one to torque one or two of the back LIM bolts to the proper setting. Make sure you get the "hidden" bolt back in the alternator bracket, and don't have to take belts, etc. off again when you discover an extra bolt at the end of reassembly like I did. duh Also, there is a pipe coming out of the LIM near the thermostat that is just pressed in with red locktite (there is a GM part # for it). Mine was leaking a lot, and being a simple tube hand pressed into the manifold, I don't see how it couldn't after a few heat cycles. With the manifold off, I'd recommend taking it out and resealing it if there are any signs of leakage. My 3.4 LIM gasket was completely intact (replaced it with Fel Pro PS anyway)- the leaks were caused by loose LIM bolts and the pipe.
 

occupant

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Messages
566
Location
Columbus, OH
Originally Posted By: ArrestMeRedZ
I bought that Lisle tool when I did a LIM on a Olds Alero 3.4 and it's worth it's weight in gold. With the new bolts (pre-applied locktite, I hope) and Fel Pro problem solver gaskets you should be good to go with Dexcool. I didn't have crow's feet wrenches, and needed a 10mm one to torque one or two of the back LIM bolts to the proper setting. Make sure you get the "hidden" bolt back in the alternator bracket, and don't have to take belts, etc. off again when you discover an extra bolt at the end of reassembly like I did. duh Also, there is a pipe coming out of the LIM near the thermostat that is just pressed in with red locktite (there is a GM part # for it). Mine was leaking a lot, and being a simple tube hand pressed into the manifold, I don't see how it couldn't after a few heat cycles. With the manifold off, I'd recommend taking it out and resealing it if there are any signs of leakage. My 3.4 LIM gasket was completely intact (replaced it with Fel Pro PS anyway)- the leaks were caused by loose LIM bolts and the pipe.
Yep, got a $17 manifold bolt set in the cart and it has blue stuff on the bolts in the picture. If not, I have blue loc-tite somewhere and I can get the red stuff if need be. In some of these how-tos I have bookmarked it describes replacing them with rubber coolant hose and worm clamps. I may do this if I notice any leakage there. That or bite the bullet and order new ones. This engine lasted through at least 2004-2005 so I'm sure I can still get them from a dealer or online (Amazon, RockAuto, Gandrud/GMOnlineParts.com). mechanicx, I think I'm going Peak Global if it's easily found locally. We don't have a NAPA in Wichita Falls, so I'm stuck with AutoZone, OReilly, and Advance, the latter two each being less than a mile away and the AutoZone about 3 miles but it's there if I need it. I'll flush it all out, have one Draintainer for the oil-milk mix and plan to buy another, maybe two, for the coolant. That way after disposing of them and cleaning them out, I'll have one for oil, one for coolant, and one for ATF for later. It's got one of those Prestone flushing tees in the heater hose line already so that will simplify things.
 
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8,576
Location
Ohio
Originally Posted By: occupant
Yep, got a $17 manifold bolt set in the cart and it has blue stuff on the bolts in the picture. If not, I have blue loc-tite somewhere and I can get the red stuff if need be.
You shouldn't need red loctite because the highest torque spec is 18 ft lbs on the manifold end bolts, within the holding capacity of blue.
Quote:
In some of these how-tos I have bookmarked it describes replacing them with rubber coolant hose and worm clamps. I may do this if I notice any leakage there. That or bite the bullet and order new ones. This engine lasted through at least 2004-2005 so I'm sure I can still get them from a dealer or online (Amazon, RockAuto, Gandrud/GMOnlineParts.com).
Some people mention the T-stat bypass pipe as being a problem area but really it usually isn't. Maybe if there is corrosion from not doing regular coolant changes or some other problem. The pipe and 0-ring is really a reliable set up and there is actually a bolt hilding the assembly down, plus the upper intake manifold captures it somewhat. If it is leaking I would inspect the pipe for corrosion and just replace the o-ring or pipe as needed.
Quote:
mechanicx, I think I'm going Peak Global if it's easily found locally. We don't have a NAPA in Wichita Falls, so I'm stuck with AutoZone, OReilly, and Advance, the latter two each being less than a mile away and the AutoZone about 3 miles but it's there if I need it. I'll flush it all out, have one Draintainer for the oil-milk mix and plan to buy another, maybe two, for the coolant. That way after disposing of them and cleaning them out, I'll have one for oil, one for coolant, and one for ATF for later. It's got one of those Prestone flushing tees in the heater hose line already so that will simplify things.
I don't think any of those places mentioned carry Peak Global or G-05 for that matter. Mostly just NAPA has it. I think Walgreens and Kmart might have Global but it might be in 50/50. If O'Reilly's still cares Havoline Dexcool that might be a good bet.
 
Messages
8,598
Location
Florida
If you really want to know if the head gaskets are leaking, get the Lisle combustion fluid tester, and hook it up the the readiator fill neck, or coolant degas bottle depending on what type of cooling system you have. I would replace the head gaskets. I have dealt with so many head gaskets on 3.1 and 3.4 engines that I take no chance.
 

occupant

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Messages
566
Location
Columbus, OH
I was going to order the 75500 Lisle kit on RockAuto for $24 but I won't need to. It's pretty obvious now that combustion gases are getting into the cooling system, I ran it with the cap off for a couple minutes just to see when the thermostat opens, and you can smell the exhaust through the opening. No sense bothering with that $24, I'm just getting the head set instead of the LIM set and I am now hoping for no cracks or major warpage in the heads. If the heads are borked I'm probably doing a 3500 topswap. The cost of buying 3400 heads is the same as the cost of buying 3500 heads and the 3400's might even count as cores for them. That's my ideal situation anyway. '98 3.4L engines put out 180hp and the 3.5L engines had 201hp. Torque is a wash. No more LIM failures, either. And if I can get a good deal from the family mechanic, I'll have the entire 3500 engine installed. Those are just as cheap used as the 3400s and in some cases cheaper. I'm actually tempted to see if a 3800 can be put in its place. But that's more of a pipedream, the 3500 is the same engine family and much easier to play with in place of a 3400.
 
Messages
36,537
Location
ME
I saw online on a cutlass ciera forum (!) someone stuffed a 3800 in a U-van and it took a bunch of fabrication. Then the poor van got wrecked. a-body.net, come to think of it, they have an "occupant" too IIRC. My shorty wheelbase 3400 was a hot rod. There's a tight cloverleaf/ bridge interchange where I have to corner at 30 MPH then merge left a lane before finishing the bridge, otherwise I'd be forced off an exit. Took the van through there, nailed a 3-1 downshift for the hail mary, and was in!
 
Messages
614
Location
Joplin
If your engine is like my 3.4L then the head gasket leak will be the front cyl. on the back side head. I think that is No. 1 cylinder - under the alternator. My LIM gasket was orginally replaced at 80K miles but was bad again by 135K. (Count me in the camp that blames and will NEVER use Dexcool - my van is happy now with G05) Let's hope the cam bearings haven't been damaged from the Dexcool in the oil. I was going to recommend doing the head's since you are this far into it. Get some PB blaster but still plan on a couple broken off exhaust manifold bolts and you will need to get a couple of new exhaust gaskets. I would go ahead and put new spark plugs and wires at least to the back bank and if they alternator is original I'd put new brushes in while you have it out. Think about a new O2 sensor as well. Take a good look at those little water hoses and the heater hoses since you will never has this easy access to them again. I would get a 10mm ratcheting wrench for the bolts that others mentioned using a crows foot - The ratcheting wrench worked great here. Don't disconnect any fuel lines just lift the entire fuel rail up and tie it back out of the way. I changed the lower fuel rail O rings since they came with the gasket set. I sent my heads to the local machine shop and had him check them all out. I had him put the new valve stem seals in as well since they came with my Fel-pro kit. I think he charged me $60 to install the valve stem seals and it came to almost $200 for all the head work - but I wanted to get it right) I remember needing some help in holding the exhaust pipe back a few inches to get the rear head to drop straight down and in place so watch out for that being in the way when you are putting the head back on. I've driven about 15K miles now since all the work and the engine is smooth and strong. It does take a lot of time and do take very good notes along the way cause you are going to be removing a lot of bolts.
 

occupant

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566
Location
Columbus, OH
That ($200ish) is what I figured the heads would cost with the valve job, I think I spent $235 on the pair of Intrepid heads with the lower intake (had to take it in because I broke off a bolt inside the lower intake) I'm seriously considering due to possible cam/rod/main bearing damage, that swapping in an entire 3500 V6 would be a better idea. The only thing keeping me from just going ahead and doing it, is I am not sure I can safely lift the van high enough to clear the engine/transaxle/cradle/front tires to roll it out from under it.
 
Messages
8,598
Location
Florida
Having a 3500 engine sounds nice, but how will the computer react to an engine with such different specifications? Since there was no 3500 engine when your van was built, how are you going to find a computer program that works well? There was more than one version of the 3500, some have no provision for a P/S pump, and some have VVT, so keep that in mind. Also, are the locations of intake and exhaust pipes the same? You might have to go to a muffler shop and have some pipes bent and welded. Locations of coolant hose flanges might be different as well, causing you to need to make changes there.
 
Messages
36,537
Location
ME
Originally Posted By: occupant
I'm seriously considering due to possible cam/rod/main bearing damage, that swapping in an entire 3500 V6 would be a better idea. The only thing keeping me from just going ahead and doing it, is I am not sure I can safely lift the van high enough to clear the engine/transaxle/cradle/front tires to roll it out from under it.
Get a cherrypicker and lift it by the bumper! Assuming you have some sweet jackstands... Put it on normal low riding jackstands. Put the crane on the engine. Undo everything underneath. Undo everything up top. Drop the mess on a wheeled creeper. Undo the cherry picker. Hook it to bumper. Lift van, guiding engine down. Stick huge jack stands under. Drag creeper out.
 

occupant

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Messages
566
Location
Columbus, OH
I'm half done tearing it down. This stuff is nasty. This goo stuff, it doesn't drain. It just clings to metal like snot to a toddler's cheek.
 
Messages
2,097
Location
kansastan
You're wasting your time if you try to modify that van. Yes, it CAN be done. But it's not practical, to say the least. You'll be time and money ahead to just fix the 3400 that's already in there. But with that much coolant in the oil, you're taking a chance. The bearings could be trashed already.
 

occupant

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Messages
566
Location
Columbus, OH
I ended up having the van towed by AAA (partially torn down) to a shop in town. I would have spent about $400 doing it my way, but the total costs to get it done including the parts I bought was $601. Can't complain, really. I did have to spend the last couple of days burping the cooling system, but it was worth it to not have to pull the heads myself. What a mess, glad I didn't have to do it myself. According to the mechanic, the heads were fine, one exhaust valve from cylinder #1 in back was burned, one intake valve from cylinder #2 in front was slightly bent not allowing it to seat properly. The head gaskets were blown on the outside edges on the front (passenger side) of the engine. Intake gaskets were both just shredded throughout but I think that was their eagerness to tear it apart quicker. Mayonnaise-like jelly everywhere. It's still in some nooks and crannies I guarantee it. This stuff does NOT dribble away. You have to wipe it off by hand, pretty much. I still have a few things to do. Broke a bleeder screw head clean off but it was closed at the time ($6), need to do an oil change at 500 miles (I'm 220 in now, filter cost $2 and then whatever oil I buy), picked up an air filter ($6) and a pair of cabin air filters ($8), and got replacement headlight and marker light capsules ($53 for the two headlights and $25 for the two markers). Also got some Wagner BriteLite headlights (2 for $10) in 9004 size. All that stuff should be here Friday or sooner. So the van drives nice for what it is. $300 van $92 battery $2.50 terminal bolts $400 head gasket labor $151 head gasket set, head bolts, intake bolts, oil filter $50 machine shop labor to clean heads $115 RockAuto for the lights, filters, bleeder screws, etc going in this weekend $8 gallon of 50/50 ST antifreeze (used all but a quart burping so far) I'm up to $1118.50 plus $20 in fuel and whatever I spend on oil for this weekend's oil change. Plus tax on 80% of the standard presumptive value of $1650 ($82.50), $33 title fee, and $52.80 to renew the tags. And I need wiper blades up front (already changed the back one, I had a 16 inch Trico left over from when I bought 3 in a closeout deal on RockAuto for the Torino). So figure $1250-$1300 all in all and sure, could I have found a nicer van for $1250? Maybe. Around here? Nah, I don't think so. I fully expect to be able to drive this thing for the winter and into spring. If the AC holds its charge I'll drive it next summer too, and indefinitely until either something major breaks or until I find something else I want to play with.
 
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