Few things are more aggravating on a race car than an engine that'salways leaking water or oil. Oil leaks make it difficult to spot cracksand other problems and generally make the car no fun to work on. And itgets worse: Head gasket failures or leaks can cause engine problems andcost you money. Fortunately, it is easy to seal up an engine nice andtight if you employ your gaskets and seals properly. Here are a few tipsto make your life easier and leak-free.

Limit the Silicone

Silicone sealer is useful in certain places to help a gasket get a tightseal, but using too much will cause problems. If too much silicone isused it will come loose and float around inside the engine. Invariably,it will find its way inside oil galleries or clog the oil screen to theoil pump and harm oil flow. Excessive silicone used on both sides of agasket will also make it easier for that gasket to move and leak. Mostengine builders only use small dabs of silicone on the corners of theoil pan rails and the intake rails at the front and back of the block.


The valve covers on wet sump engines have vent holes for a reason. Ifthe engine isn't properly ventilated, the crank pressure will builduntil an engine seal gives way in order to vent the air pressure. Whenthat happens that particular seal is going to leak from there on out.For circle-track engines you need at least one large air breather (coverit with a filter to keep dirt from getting in) on the left valve cover.

Head Gaskets

Ken Troutman of KT Engine Development says most head gasket failureshe's seen aren't because of poor quality gaskets. They come from outsidesources. One of the biggest culprits is poor block prep at the machiningstage. If the deck of either the block or head isn't square with asmooth surface, you are going to have sealing problems. Machine marks inthe deck from the cutting operation is OK, but in Troutman's words, "Ifthe deck looks like it has been cut with a file, you know you are goingto have problems." Another common reason for head gasket failure is poorclamping. Head gaskets require proper clamping pressure, applied fromthe head bolts or studs, in order to seal properly. If you are usingpoor quality head bolts or are reusing torque-to-yield bolts youprobably aren't providing the head gaskets enough clamping force to sealproperly. Quality hardware designed specifically for racing, like thehead bolts sold by ARP, are necessary because there is a tremendouslifting force every time the fuel/air mixture is detonated in amedium-to-high compression racing engine.


Some intake manifold bolts on Chevrolets extend into the lifter valley.Use a good Teflon sealer--not silicone--on the threads to keep oil fromwicking up the bolt and puddling on top of the manifold.

Watch the Blind (Holes)

Some head bolt holes on some Ford blocks are blind holes, meaning theydead-end into metal. If you try to use a head bolt that is too long thebolt will just butt into the end of the hole and go no farther. You willget the torque reading you are looking for, but the bolt will not applythe proper clamping load between the head and the block. When usingbolts in blind holes, check to make sure the bolt cannot reach the endof the hole or use studs instead.

KT Engine Development
Automotive Racing Products (ARP)
531 Spectrum Circle
CA  93030
Cometic Gasket
26555 Northwestern Hwy.
MI  48033
Corteco Clevite