I have been a diesel mechanic for about 4 years now and have done a fair amount of work on these beloved 7.3's. Until recently when a customer would come in for an oil leak 9 times out of ten it would be caused by either the O-rings leaking from the Head outlet fittings or the rear plug on the high psi pump. But sometimes the plug that is under the two outlet fittings about 2 inches from the left head would leak and now here lies the problem. Ford does not offer the smaller o-ring for the plug so what I did once was take the plug out and replace it with a Caterpillar high temp o-ring and everything was great. I guess you would not call it a plug because it seems to be a plug/holder that holds some sort of valve in place near the high psi regulator. The first time I did it the truck started up great and no leaks. But today one of the other mechanics did the same procedure on a different 99-03 7.3 and the high psi pump would not build any psi. So we replaced the pump but now the high psi system builds too much psi 3000 psi+ at idle which is way too much. The injectors also do not sound right. On the old pump we investigated it and the only thing that came out of the plug is a funky looking valve. So are we not doing something right here? Are you not supposed to remove this smaller plug? Also today I did another small high psi plug and when I went back in with it the plug would not get tight and it puled the threads out of the pump. I did not cross thread the plug I guess the threads just took a S%#@. But I guess it is bound to happen with a steel plug and aluminum threads. So I just want to know what is going on? Does anyone know what these plugs are for and what that steel valve does?

Thanks
John

 

Hello John, that must be Fords unserviceable plug. Do a search for GUZZLES O-RINGS on here. You'll come up a link to his site that explains the proceedures for removal and replacement of that o ring.

 

i agree with fifthwheel.

I also wish more ford mechanics would come here to find out how to fix these trucks right lol.... good job john.....

 

Did you lose the check ball?
You have to have the pump oriented correctly before you remove the plug.
Also helps to heat the plug first to break the loc-tite bond.

 

Dieselsite.com has a replacement plug with longer threads for the "non-replaceable" plug if you have one stripped out. You have to take out the HPOP to replace it or the ball in the valve will drop out! International has this part as well.

 

You can also get a replacement plug from an International parts dealer pn# 1842906C91. The issue is the the one that is originally in there is short and does not have enough threads for a solid engagement. Over time it can loosen and begin to leak. The Diesel Site plug and IH plug are the same (Diesel Site machines theres as a match to the IH replacement). This plug has more threads for better engagement strength.