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buick upper intake gasket on 3.8 v6
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dog_4003
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Apr 7, 2009, 8:45 PM
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buick upper intake gasket on 3.8 v6
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i have a 1996 buick regal custom with a 3.8 v6 engine. the upper intake gasket was leaking coolant. and i replaced it. how ever it has lost a little coolant over a period of time. i have filled the over flow bottle twice since i replaced the gasket. now the engine ran fine before i replaced it other than the coolant leak. the engine ran fine after i replaced the gasket other then the coolant dissapearing. untill tonight. i was driving it home from now and the engine started misfiring and lost all power. so i had the car told home. when i got it home and tried to restart the engine. the engine was hydralocked. so i emptyied all the coolant out and the engine finially started and ran like a bran new one no misfires or nothing other then steaming and smoking bad as iff it had a cracked head. now its been abought 4mths since i replaced the upper intake gasket. and its ran fine no over heating or no issues. i havent done nothing yet but empty out the coolant. any ideas where the leak might be or what gaskets to check first. thanks
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dog_4003
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Apr 7, 2009, 9:34 PM
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Re: buick upper intake gasket on 3.8 v6
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also i forgot to mention that the oil in the engine is of normal color and its clean there is no milky look to the oil as iff thee was coolant in it. thanks
(This post was edited by dog_4003 on Apr 7, 2009, 9:35 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 8, 2009, 2:06 AM
Post #3 of 8
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Re: buick upper intake gasket on 3.8 v6
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Is this to say it's empty of coolant now and runs fine in test while empty? That coolant leaking fast enough to lock the engine is a pretty fast leak into cylinder. Pulling plugs would release the hydraulic lock - not certain why draining the coolant helped that at all as that coolant went somewhere - burned thru or passed into oil and is sitting on bottom of oil not mixed in yet to make it milky.
Sounds like you may have escaped severe damage from hydraulic lock - a compression test while still intact could be very informative now and my guess is you should go redo the intake gaskets and probably go all the way and do head gaskets and send the parts out to machine shop for close inspection too. Do as much testing now while intact. The missfire could be a simple as a very wet plug. The smoke could take a while to clear up especially coolant into exhaust would take some time to burn off AFTER any leaking has ceased.
Take a good look at cylinder walls and pistons for damgage. Plan on new plugs, antifreeze, any hoses still original and an oil change with the job,
T
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dog_4003
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Apr 8, 2009, 7:21 AM
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Re: buick upper intake gasket on 3.8 v6
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yes its empty of coolant now and runs like a new one after i empty the coolant the engine after abought 30 min of trying to start it finianlly worked out the coolant and cranked. i am going to recheck the upper intake gasket i replaced . thats what i was kinda thinking my self that it may be leaking. ill let you know how that turns out when i check it. thanks for reply.
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dog_4003
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Apr 8, 2009, 7:26 AM
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Re: buick upper intake gasket on 3.8 v6
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oh also i emptied the coolant my self to try to get the engine to start when it was hydralocked and it worked by letting the coolant out the engine did crank and run fine. now the leak wasnt to bad. it used maybe half gallon antifreeze every month or 2 with abought a 150 miles a week put on it for work. i am going to recheck that upper intake gasket and see iff it might still be leaking and will let you know when i do.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 8, 2009, 8:08 AM
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Re: buick upper intake gasket on 3.8 v6
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The generic pic for reference:
OK: It was leaking way too much at even a 1/2 gal a month! It probably was enough to foul one or more plugs and cause the tow while engine was still under basic cooling system pressure the liquid continued to enter the combustion chamber of probably just ONE that caused the lock. Attempting to start it while locked with liquid puts INCREDIBLE forces on everything there and the weakest link would finally give out OR perhaps the slight leak that allowed coolant in was able to return enough liquid backwards to allow engine to turn again and run.
Antifreeze is a bit thicker than vapor or even liquid fuel which will leak past rings so it might not have found its way into oil but it had to relieve the pressure somehow - with it leaking to some place slowly or breaking something - that's what worries be now! That cylinder was in "compression" mode so intake gasket should be out of the picture for relieving the pressure.
Once locked the head gasket would be a weak link, piston can crack or even a cylinder wall make a slight split into water jacket. Maybe NOTHING happened or broke and it's all just gasket - can't know that right now.
Know this: A starter motor is strong enough to break a piston, bend a connecting rod and I seen then snap a chunk right off the engine block where mounted!
Go heavy on diagnosis on this as it may take a whole job to then find there was more damage. Hard to guess on that,
T
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dog_4003
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Apr 9, 2009, 1:38 AM
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Re: buick upper intake gasket on 3.8 v6
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heres an update. i rechecked the upper intake gasket today and it did seem to be leaking. the upper intake was has antifreeze all in it so i absorbed the antifreeze with paper towles and put some cylacone around the water ports on the gasket and it still seemed to leak. so the ? is why is it leaking and not sealing. cyclenders started to fill back up with water so i shut it down before it hydrolocked again. now i did notice that when i took the upper intake off it looked as iff it is sucking the antifreeze threw the throttle body possabley. there was alot of moister on the back side of the throttle body and in the inside of the upper intake. any subgestions on why it would be sucking antifreeze threw the throttle body or why the gasket is not sealing or could the water in the throttle body be due to the gasket not sealing. thanks
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 9, 2009, 5:07 AM
Post #8 of 8
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Re: buick upper intake gasket on 3.8 v6
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I simply don't know the exact configuration of every engine but intake manifolds will also be sealing antifreeze and exhaust as well as securing/controlling the incoming air flow.
Head and intake gaskets can leak any which way of anything they are there to seal. Coolant, oil, pressure, to outside or get drawn in unseen. Back when coolant was directed thru some chokes right at the carbs.
So: With that, the items, manifold itself which may be two units, the heads, or not so likely with this case the block made of cast metals or even plastics can crack and fail as well. Some can get hairline cracks that only show up to the eye at certain temps. Machine shops can check and resurface certain parts or repair to a point then a new part would be in order.
Perhaps when doing the gasket the first time it got damaged or some material (anything) got in the sealing area.
If that leak can leak into the incoming air or air/fuel mix it goes on to be burned and as you know if overloaded as a liquid the pistons won't compress. If that was a sudden overload while running the engine it would almost certainly break engine parts. Just cranking has a chance of NOT breaking parts but a starter is stronger than most folks realize.
The sealing action for compression is not 100% tight. Some air/vapor will escape past rings and valves. Fuel is less viscous and can pass thru rings - more viscous liquids may not.
The original leak may have been more than just a gasket. Leaking antifreeze commonly goes without notice till an overheat happens which can cause unknown levels of damage as well. Warpage, cracks etc.
Note: Sealing things from the outside is not really a viable solution for engines. Sometimes you can get lucky in an isolated case.
This will need to be tested every which way to find the flaws EXACTLY. Cooling system pressure test could target an area when all is intact. Once apart it may take the calibrated equipment of a machine shop. Warpage in particular is not always clear to the eye,
T
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