billv45

Well after correcting my boost leak my crappy 12 Mpg jumped all the way up to 13, crap. Could a maladjusted TurboMaster Wastegate cause such poor mileage? The PO told me to back off the adjusting nut on the TurboMaster wastegate to bring the boost down to around 18 if I took out the Bosch 370's and went back to the stock injectors. Which I did, so I back it on out. I figured it would be just a few turns but it took quite a few to get the boost down to 18 max.

Is 18 max boost too low for a '96 12V stock with a BHAF (and a TurboMaster wastegate)?

billv45

No one has an opinion on boost?

Lary Ellis (Top)

Seems like 18 lbs is about max on a stock 96, maybe around 20. But I really don't think that is your mileage issue. I would open the TM up and let it have all the boost it will generate as it will pretty much balance out via the amount of fuel you are putting out.

Since you don't have a fuel plate in it, too much boost would not be an issue at this point. I would suggest looking around to be sure you have no more leaks and A valve adjustment might also be in order.

I get much better mileage out of my 96 and I have an extra 102hp according to the dyno. Something is not right, when was the last time the fuel filter was changed? Is the radiator and intercooler clogged with bugs or bent fins?

billv45

Fuel filter is new (a few hundred miles ago.) Radiator and intercooler are clear and in good shape. I pulled off my air filter and stuck in a PVC cap with a air valve stem in it to pressurize my boots to check for leaks and that's when I found and fixed that one. There were no other leaks and the system held pressure for a minute or so (until I got tired of waiting.)
Opening the TM would mean tightening down the adjusting nut, right? If I understand the TM correctly, the spring is applying the pressure to keep the wastegate closed and it opens up when there is enough pressure to override the spring, right?

Abbynormal

Just throwin out more suggestions. As Lary said , get your overhead valve adjustments checked, maybe get your timing bumped to around 15*, replace the overflow valve in the injector pump. As Lary said boost up to 28 pounds won't hurt mpg. Could you have restrictions in your cat or is it gone ? Also try synthetics in your differentials and transfer case. For that matter I would go synthetic everywhere you could. Does the truck start easy ? If it doesn't maybe there is a vacuum leak in the fuel lines somewhere. Does your truck smoke much, what color ?

wannadiesel

I'd want to see about 24 psi. Run it back in a bunch.

The lousy mileage is probably due to slipped timing.

billv45

Cat is gone. Fresh synthetic Lucas fluid in the diff. Truck starts easily and doesn't smoke much at all. I had a vacuum leak that was causing havock with my ABS/Brake lights but it's resolved. I can shut the truck down and there's still vacuum in the lines a minute later. I still have not checked fuel pressure since I'm waiting on a new banjo bolt from the dealership (don't like drilling and tapping without a backup on hand.) Now I do have the BHAF but have not made the heat shield yet (it's on my "To Do" list) but it's still pretty cool here in AL.

So, barring a bad transfer pump, it looks like it's time to check the timing and valve adjustment after I replace the overflow valve for grins. I may be able to handle the valve clearance check (but I have not looked into the procedure yet, is it hard?) but don't have the tools for the timing check/adjustment. Should I invest in the tool kit (how much is it?) or just try and find a good shop around Birmingham AL?

marine4life

Snap on has a timing kit for $215, has everything you need, just got mine.

billv45

Snap on has a timing kit for $215, has everything you need, just got mine.

$215 isn't too bad. I was expecting almost that for someone else to do it. What's the part number on that Snap On kit?


I just call my local dealership and a overflow valve part number 04883838AB was $159 list. It was part number 3963593 at Cummins and cost $96 (and what the heck was the 2 417 413 101 000 part number that I found when I search this forum?)
Is the OF valve a dealer or mail order item only? Can I get my hands on one locally without signing for a loan?

TxDiesel007

HA!!

those prices are insane!!

Marty Tompkins is the name u gotta know, type it in the search forum and he sells OF valves for 35 bucks.. U will not find it any cheaper and its a two minute job to replace...

Rick

Abbynormal

If you cant find him Piers (PDR or Piers Diesel Research) has overflow valves for about $55 i think.