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My husband and I have just purchased a 1994 Isuzu Bighorn to tow our boat. I have been told there is a problem with the compatibility of the engine seals and the diesel fuel itself with this model?


From the "Ask Jack" archives


When a lower sulphur content was introduced into our diesel fuel (for health reasons and to ensure the availability of the most up to date diesel technology in new vehicles) late last year, there were some reports of external fuel leakage past the injector pump seals on older diesels (mainly used imports).

In cases like this, the injector pumps needed to be stripped down and overhauled with new seals etc. Not a cheap repair unfortunately.

Sulphur in the fuel could actually cause a swelling of the pump seals which in fact allowed older diesel injector pumps to run a lot longer than they should have without reconditioning. With the reduced sulphur these seals tended to shrink back to their original size and this is where the leaks started.

It was, and still is, considered normal wear and tear if these sorts of leaks develop. If your Isuzu is currently 'leak free' then you have nothing to worry about at this stage. The pump may have been overhauled sometime in the past.

It's one of the risks of owing an old diesel CJ.

Engine related repairs can be very expensive.