Injector Cup Seals [Archive] - TheDieselPage.com Forums

More Power

10-14-2002, 16:41

Duramax Tech
Injector Cup Seals
By Jim Bigley

http://www.thedieselpage.com/members/duramax/injectorcupweb.htm

After being deluged with bogus rumors about cylinder head failures for over two years, a lot of people have been on pins & needles waiting for the other foot to drop. Fear not, there have been no confirmed cylinder head failures that we're aware of. However, there have been cylinder heads removed and replaced for other reasons. This story is about one such reason.

Diesel Brad

10-14-2002, 18:51

Great article, Jim. Nice to finally be able to silence all of the claims that "aluminum heads don't belong on diesel engines." The pictures were great, too.

Keep up the good work!

mackin

10-14-2002, 18:59

MP

Excellent article !!!!!!! Much appreciated info ........

MAC

chuntag95

10-14-2002, 21:11

Since I had the leak around the cup on cylinders 2, 3 and 4, I was glad to see the cut away. Makes more sense now. I didn't get to see them out because they were stuck and the extraction tool was on back order. I was one of the people who's coolant just vanished. Since the repair, not a drop lost. Mileage on the first tank seemed to be better, but time will tell it there is really a difference. I track every tank and am at ~16 mpg lifetime. I would like to see that creep up, but considering this is the most fuel effecient vehicle I have EVER owned, I guess I can't complain. It is also the largest. :D Thanks for the light to my plight.

hoot

10-15-2002, 05:35

MP,

Would simply tightening the injector fix the problem?
Or does the seating area become contaminated?

It really is a simple design.

[ 10-15-2002: Message edited by: hoot ]</p>

Kent Tuttle

10-15-2002, 08:21

Jim,

Do you feel the two o-rings at the top of these cups could become a problem when our trucks get really high miles on them? Nice article, great info as always!

More Power

10-15-2002, 10:08

I've yet to hear of a coolant leak past the two large o-rings. Time will tell if this becomes a problem in the years to come. The o-ring composition looks like Viton or some other new material. Viton has been used as seals in fuel injection pumps and for rear main seals for quite a few years.

The smaller bottom-end injector cup seal looks to be a black, possibly a carbon composite seal (just an educated guess). The leaking seal photographed for the above story had been nicked during assembly (according to the GM diesel tech who did the work), which resulted in a compression leak very early in the life of the subject engine.

That photo was taken in February, of a new '02 GMC cylinder head.

MP

[ 10-15-2002: Message edited by: More Power ]</p>