350 Intake Manifold Gasket Leaks

Ken D

Junior Member
Last falI I picked up a nice clean '88 VanDura 2500 van to be used for pulling our 16' travel trailer. It's got a TBI 350, 4spd auto (TH400?) and 3.73's. I tucked it away for the winter (to keep it in the condition I found it in!) and plan to use it summers only as a hauler. There's about 90,000 miles on it, and it runs like a watch,*BUT* I've been told that the intake manifold gaskets go on these engines and I should change it as "routine service" on this engine.(The guy also claimed that when this happens coolant is pulled into the bottom end, taking out the bearings. This is when my B.S. detector started alarming.) Regardless, are these intake gaskets prone to leaking "routinely"? Heading for the west coast this July and don't need that ... rather change it now. Thanks from a first time poster.

John DiMartino

PlowSite.com Veteran
I have worked on several TBI 350's,and occasionally they will leak anti-freeze out the intake-but usually it leaks externally down the front of the block and on the ground.It is rare that it leaks into the intake valley-but it is possible.I have never seen it though.You have the TH700R4 auto if it has OD.Just keep it serviced,add an aux cooler if your towing,and dont tow in OD with heavy trailers and itll hold up well.Keep it in drive towing that 16 ft travel trailer.Intake manifold gaskets are never routine service,and are rarely needed on any motor unless there is a recall or defect.


Junior Member
Yes it is fairly common . I have repaired about 8-10 of them about 50-50 weather they leak inside or out, usualy caused by not changing anti freeze. Also if you have the intake off look for signs of head gasket leak or block cracked in lifter gallery. Some 88&89 small blocks cast in mexico were prone to crack.