Jolly_John Posted January 17, 2009 Share Posted January 17, 2009 Hi, Gang. My son-in-law (and his mechanic) thought he had experienced the typical upper intake manifold coolant leak on his non-supercharged 3800 engine. He had the plastic upper intake manifold and gasket replaced....but the coolant leak still exists. The engine is consuming about a half a cup of coolant every couple of days, plus there is a little external pooling of coolant between the upper intake manifold and the engine head (the head closest to the front of the car).The lower intake manifold gaskets were NOT replaced when the upper job was done, and the mechanic now indicates that might be the source of the ongoing problem. The mechanic also stated the lower intake manifold could be warped. That was just a comment though, not based on any troubleshooting or disassembly. My questions: In searching the internet, I found lots of info about this GM 3800 engine collant loss problem. However, the possibility of a warped lower intake manifold was never mentioned. Does anyone have a comment about the liklihood of this (the car has never been overheated)?Second, if the lower intake manifold gaskets are bad, how in the heck would that cause the coolant pooling we're seeing up on top between the upper intake manifold and the one head. I guess I don't understand the theory on that. Any comments would be appreciated. Thanks, John Link to comment Share on other sites More sharing options...
D-a-n-i-e-l Posted January 17, 2009 Share Posted January 17, 2009 You must be talking about a 3800 from 1991 or newer. I would look at what kind of gasket was used, and if the gasket had the improvements incorperated into it. I would buy a Fel-pro gasket and re-install. There were a couple improvements over factory that make for a much better gasket, ie.. metal rings to ensure the gasket is not prone to failure from overtightening, from those who choose not to use a torq wrench. Link to comment Share on other sites More sharing options...
Barney Eaton Posted January 17, 2009 Share Posted January 17, 2009 Jolly John did not mention the year but I believe it was around 1996 when GM put the plastic intake on the 3800.Reattas do not have this problem.My question......what kind of mechanic would only replace the upper gasket when he had the intake off the car? Link to comment Share on other sites More sharing options...
charlie1 Posted January 17, 2009 Share Posted January 17, 2009 (edited) ZZZ Edited August 2, 2009 by CHAS1 (see edit history) Link to comment Share on other sites More sharing options...
Guest squiretom Posted January 17, 2009 Share Posted January 17, 2009 my 91 had the intake gasket replaced at some point in time. they also used some blue formagasket stuff and i will have it done again.in the attached pic , is it possible that coolant is leaking from manifold gasket or head. area shown is wet and green but no discernible loss of coolant or vapor from the exhaust is noticed.car runs great. Link to comment Share on other sites More sharing options...
padgett Posted January 17, 2009 Share Posted January 17, 2009 There is a small coolant tube under the throttle body that I have seen corrode - did you chaeck that ? Link to comment Share on other sites More sharing options...
jonlabree Posted January 17, 2009 Share Posted January 17, 2009 It goes into and thru the throttle body. Link to comment Share on other sites More sharing options...
Guest squiretom Posted January 17, 2009 Share Posted January 17, 2009 thanks for the tip , i will look into that soon. i hope that is the problem. i think i will redo the manifold gasket also. Link to comment Share on other sites More sharing options...
D-a-n-i-e-l Posted January 17, 2009 Share Posted January 17, 2009 Some of the 3800 started to get the plastic intake as early as 91'. Unless the couple regals I have seen in that year had a motor transplant. The funny thing is these cars were still running the older trany, not the electronic vesion. Link to comment Share on other sites More sharing options...
Rawja Posted January 17, 2009 Share Posted January 17, 2009 <div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Some of the 3800 started to get the plastic intake as early as 91'. </div></div>Yeah, I'm pretty sure my '93 Trans Sport's 3800 has the plastic intake manifold. Link to comment Share on other sites More sharing options...
Guest Reatta1 Posted January 17, 2009 Share Posted January 17, 2009 While you are pursuing this problem, I'd strongly recomend that you keep an eye on the oil. Look for any signs of coolant getting into the crankcase. My daughter had a coolant leak problem on her Skylark and it ruined the bearings. She had to replace the engine. Link to comment Share on other sites More sharing options...
Guest squiretom Posted January 17, 2009 Share Posted January 17, 2009 oil is clean and no foam or other film in the coolant tank, that is why i am looking at other areas for leaks. also had a leaking pan gasket replaced and so far nothing in the oil pan indicating a problem.just for grins and giggles , what are we looking at in replacing the head gaskets ? does the motor have to be pulled ? Link to comment Share on other sites More sharing options...
Ronnie Posted January 17, 2009 Share Posted January 17, 2009 Buy or borrow a kit that has a pump and a special radiator cap for pressurizing the cooling system. Clean everything up on the manifold. Then attach the kit and pressurize the system. Watch for external leaks. Link to comment Share on other sites More sharing options...
Guest spamseptictank Posted January 18, 2009 Share Posted January 18, 2009 You may want to invest in a UV dye leak detector kit. I borrowed one from a friend and found the leak in my wife's 97 Firebird's (3800 Series II) heater transfer tube. It's a plastic 90 degree elbow that connects the intake manifold to the alternator/ heater hose/ belt tensioner pulley.FWIWGrace and Peace,Dave Link to comment Share on other sites More sharing options...
charlie1 Posted January 18, 2009 Share Posted January 18, 2009 (edited) ZZZ Edited August 2, 2009 by CHAS1 (see edit history) Link to comment Share on other sites More sharing options...
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