Maintenance day

[BJMarshall]

Alright, I spent most of the day PM'ing the 91 I just bought and I've got a couple of questions.

I did all the basic service stuff (oil, filters, grease and such) I changed the transmission oil and overfilled it with Mobil1 5w30. This made a big difference in the transmission noise and shifting.

I want to know what the best stuff to put in the differentials and the transfer case is?

On the front brakes, can the rotor be separated from the hub? Didn't look like it to me, but what do I know. Rotors are a little warped and looks like they have been turned before. I was just going to replace them.

I've got some pretty serious chatter in the clutch. What is the recommended clutch for these trucks? I'm going to try and get it apart one night this week and get the flywheel surfaced, and I wanted to get a clutch so I can put it back together this weekend. I just want to get a good one so I don't haave to do this again in the near future.

I've also noticed in the first couple of weeks driving it that unloaded, the rear brakes will lock up with very little brake pressure. I don't see anything leaking back there and the brake fluid level hasn't changed. What would be the first thing to look for on this?

Sorry for the book. Just want to make sure it will run another 250,000

 

[Greenleaf]

How-dee Paaat-na. (ya gots ta say it quick,'er people will think yer slow)



Brakes; will require a press to R&R the studs. The rotor will come off when the studs are removed if I remember right. Then, it'll need to be turned to "true em up" once the new studs is set. I'm ain't no English teacher. I just play one on TV.



The Lock-up/grabbing;

Probably the rear anti-lock is not working and or some dude unhooked it.



Scott

 

[dan brooks]

I used a hammer and brass punch to drive the studs out of the rotors and drums. The brass is softer than the studs so it won't damage the threads. You can drive them back in the same way, use an air impact wrench with some washers under the studs, or an air hammer if you don't have access to a press.



Besides an ABS malfunction, the rears grabbing could be caused by a few other things - a leaky axle seal contaminated the shoes, or the shoes are worn badly and the rivets are grabbing the drum (mine had two nice, deep grooves after ~50k miles).



While it's apart, and if it hasn't already been done, swap in 3" shoes instead of the 2. 5" that came in it. It will give a nice improvement in stopping power.



Can't help with the clutch - I'm running a slushbox.

 

[dpuckett]

Clutch recommendations

Personally, I'd stay with the Sachs clutch if you're going to stay under 300 HP and not abuse it. (note to self: have to quit assuming everyone else drives like the old man that I am). I had a stock clutch-nearly stock engine for 220K- start getting a little warm after some tuning on the engine, then the adaptor between the t-case and transmission went out. I ordered a LuK ProGold, as I thought the clutch had gone out. Turned out not to be the case, but there was a 25% restock fee for the clutch, so I put it in. Didnt hold as well as the stock clutch with 225K. So personally, I'd steer clear of the LuK.



I would see about getting the flywheel turned, but then you run into problems with the clutch maybe not being even, so it's be best to do it all together at once.



Daniel

 

[BJMarshall]

I'm sure I am well below 300HP. It's not abused and it's not used to tow much. EGT's are a little high when towing. I have to keep an eye on it. I have a water to air aftercooler with the correct fuel lines that I salvaged from a skidder. No leaks and it appears to be in good shape. Do you think this would help lower the EGT's?

 

[BJMarshall]

Anybody???

 

[cerberusiam]

Any intercooler should be better than no intercooler even if it is coolant water. Your minimum air charge temp will be limited to the maximum water temp but that will probably be less than what you are at now under boost.



There are a couple of threads discussing this and the marine aftercooler if you want to search for them. Somebody had done a test on air temps and if my memory is correct the temps under boost were at and above 300 degrees at the turbo and down around 160 at the manifold with the stock air-to-air IC. All things being equal you should see some help with the water to air IC.



If you can plumb the flow from the radiator correctly and get the flow high enough to cool it should help. Did you check the line size and to make sure the skidder stuff was the same? I remember hearing that the connections may be different to the pump and injectors.



Be interesting to see if it will fit and how it works.

 

[NIsaacs]

BJMarshall, I have the factory water cooled aftercooler on my Ford, see sig. Cummins used them for years on their diesel engines, even after most manufactures went to intercoolers. I like them, they are simple and have less boost loss at the manifold. The main drawback is if they leak, you have problems. If you have the hood clearance, I would install it.



"IF IT AIN'T CUMMINS POWERED, IT AIN'T A TRUCK"



"NICK"

 

[dpuckett]

Not to knock the water to air intercooler, but I prefer to keep my water and air as far apart as possible. I saw an aftercooler set up like Nick mentioned in a Chevy, and they had to do a 3" or 4" body lift go get it in there, plus there is the plumbing to consider- the manifold was radically different in the Chevy. I wasnt aware of boost loss in an intercooler, at least not in our app.



Since you have a 91 grille, I'd go for an intercooler. I think I still have the email of a guy who has one from a 92. PM me and I'll get back to you.



-DP

 

[JLEONARD]

I have an antifreeze cooled intercooler on my marine Cummins... a 1999 6bta rated at 270 hp. For obvious reasons an air to air intercooler is not practical in marine applications.

In the marine apps. . the 220 hp is not intercooled, the 270 is antifreeze aftercooled, and the 315 thru 370 is sea water aftercooled.

I understand via Greenleaf that busses also use the antifreeze cooled intercooler.

Bottom line... it should help a lot.

Jay

 

[1stgen4evr]

intercooler/aftercooler

This has been said before and at the risk of offering advise that isn't appropriate- - - -



I think the aftercooler BJ is talking about is on the intake manifold and has water plumbed to it. Standard Cummins on higher HP engines. It is used with and without an air to air intercooler.



It increases density of the charged air so that more fuel can be pushed in for a higher hp engine. My guess is that it will have no reduction on egt.



I'm with Daniel as to the clutch. I have gotten very good service from the Sachs. I have in the past taken a clutch out and buffed the surface to stop chattering. Your truck may have had a driver that slipped the clutch and glazed the surface. Also sanded the flywheel the last time I had my clutch out to change the pilot bearing. The only reason to resurface the flywheel is if it is cupped. Typically the pressure plate will be out of spec long before the flywheel.



1stgen4evr

James