Engine/Transmission (1994 - 1998) New to me 98 12 valve with some wierd stuff on it????????

[DonFitzwater]

I just bought a used 98 12 valve 3500/5speed today and it has some screwed up stuff done to it and I would like some clarification as to why it was done. The main issue I need info on is the turbo, more specifically, the wastegate. The pressure reference line that usually goes to the wastgate from the compressor side of the turbo has been disconnected from the compressor and t'd into the afc housing on the fuel pump along with the intake pressure reference line? So basically, the waste gate and the intake are plumbed together and the hole in the front of the compressor has just been left open! I'm a little confused to say the least. I have to drive the truck from Dallas, Tx to Lafayette, La tomorrow so I topped off all the fluids and just plugged the compressor hole with a 1/8 pipe plug for now. Why would the previous owner have done something like this? Is is a method to cheat for more boost? It sure seems like somebody was a little low on brain pressure when they just left the compressor wide open? Fyi, it's got 176,000 miles on it but runs really well... ... ... ... ..... other than that air leak kinda noise that I was hearing all the way from where I bought it today? Thanks in advance! I'll update my profile later now that I'm back in the 12 valve business!!!!!!Yippeeeeeeeeeee!!!!

 

[TPCDrafting]

The pressure line running from the back of the AFC to the wastegate is stock. If the fitting where the line goes into the AFC is straight, it is likely stock, but if it's a 90 deg. elbow with a small allen head screw, it is likely aftermarket. The hole in the compressor housing is not stock, it may be an aftermarket compressor/housing like a hybrid 35/40 setup. By plugging that hole, you should have a greatly increased boost/performance. I ran mine down the road once without the plug and lost about 10 lbs of boost and lots of power.

 

[DonFitzwater]

The turbo on this truck appears to be stock, it still has black paint on the compressor side and the attaching hardware doesn't appear to have been disturbed so my best guess is it is the original. . My 97 only had a reference line from the intak to the afc and a reference line from the compressor side of the turbo to the wastegate. Are 98's different? Is the line that is connecting the wastegate and afc there to cause defueling when overboost is present?

 

[Dieseldemon]

Both types do the same job to open the waste gate when it gets to the preset level

 

[DonFitzwater]

I made it to Lafayette in 9 hours, 505 miles, and six gallons of oil! I blew, literally, the rear main seal at Longview and lost oil pressure. I got lucky and nothing "appears" to be damaged. I dumped in a couple of gallons of oil and stopped every hour and a half to top it off. I did manage to get 24. 6 mpg on the trip... ... ... ... ... ... . I think I did better on fuel than I did on oil! Anybody in Lafayette wanna help me tackle a rear main seal one night? Just kidding, I'll limp it back to Dallas on the 17th and fix it there. PS, I did plug the hole that some dummy left open on the compresser side and surprisingly, I got a little less smoke on hard acceleration. I will put some guages on this thing after I get back to civilization so I know what in the heck is going on with this thing! I'd rather push this Dodge than drive my Dad's FERD! (I hope I don't have to eat my words!)

 

[WDixon27]

if i had not messed up a hand a week ago in a wreck id offer my tools lift and a weekend night, but i can't even work on my stuff at the moment

Anybody in Lafayette wanna help me tackle a rear main seal one night? Just kidding, I'll limp it back to Dallas on the 17th and fix it there.