Gorilla Snot

We recently had a Citroen DS23 in the workshop for a number of jobs, one of which involved checking the oil filter bits were all intact as the previous service had been carried out by a local garage, rather than a specialist.

Luckily the oil filter bits were all present and correct, but when I was cleaning the bits to put back in, I discovered something very worrying. The gauze pre-filter that the oil passes through before entering the paper filter was almost completely blocked up with stringy, rubbery bits.

It turns out that when the garage fitted the new filter they had a problem with the cover plate gasket leaking. Their solution was to remove the plate and gasket and apply excessive amounts of “gorilla snot”, otherwise known as silicone sealer, RTV, instant gasket etc. to both sides of the gasket and refit. This stopped the leak all right but when they did up the plate, the excess sealant squeezed out of the joint. What squeezed out to the outside they would have wiped away, but what happens to the stuff that squeezes out into the engine? In use it breaks off and is carried around in the oil until it lodges somewhere, usually restricting or blocking the oil flow, which is what happened here. This is why this type of sealer should NEVER, NEVER, NEVER, EVER be used on an engine unless the engine has been specifically designed for it. Many modern engines have a groove which you put this type of sealant into rather than using a gasket, but our classic engines are not like this.

Any good automotive engineer will tell you this and I do not even have any of this sealant in the workshop. It’s not necessary and it is dangerous when misused.

Leaks from the oil filter cover plate are usually caused by distortion of the plate around the bolt holes. When it is tightened up the bolts pull the part of the plate by the holes closer to the sump. When the plate is off, it should be placed on a solid flat surface and tapped back flat with a medium sized hammer. Once clean and flat, a minimal amount of your chosen gasket sealant (not silicone!!!!) should be applied to the plate and the gasket pressed into place. We prefer using a good quality non-setting gasket sealant like Hylomar Universal Blue, and even then, very sparingly. Make sure the sump face is clean and dry, all traces of old gaskets or sealant having been removed, then smear grease on the face of the gasket that sits against the sump and bolt it on. Do not over tighten the bolts which all should have shake proof washers fitted.

Doing it this way, I’ve never had a sump plate leak and it is easy to disassemble the joint next time you need to change the filter. Using Gorilla Snot is not necessary and is likely to wreck your engine if misused! You have been warned…..



2 Comments on “Gorilla Snot”

  1. AlGrayson says:

    Anything wandering around in the sump can be drawn into the oil pump, which is not good, but once past the pump it will be caught in the filter, not continue around the oil circuits.

    • On D models the filter is before the pump, but I have seen the filter mesh virtually blocked by strands of gorilla snot. Either way it’s nasty stuff to use on an engine.

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