08 Mack GU713 Granite Fan replacement?

[deercreek]

We have a 2008 Mack Gu713 Mp8 daycab truck that we bought with some body damage and are fixing up. This is our first mack and still trying to learn the ropes on this. First off, the truck layed over on the passenger side, the truck runs and drives great with no loss of oil and good oil pressure. Have a few things that came up and hoping maybe you can help me out with:

1st: There was some tranny fluid leaking and finally figured out it was coming from the power steering oil cooler(passenger side frame rail), the power steering wasn't working either. It looks fairly easy to replace but was wondering if I can replace the cooler without draining the tranny fluid and not making a big mess? Or would it be best to drain and then replace?

2nd: The fan schroud had a few bends in it and also the fan got one of the blades partly torn off(about a 3 inch piece off the corner). Is it a big challenge to replace that fan, (it's only one of the blades, could maybe just run it as is but not sure?). Does the whole clutch have to come off as well?

Thanks alot for your help and can't wait to get this thing all fixed up and running down the road.

[joes mack]

if i remember it should have a alum fan guard and it should have 6 or 8 bolts holding it on take the bolts out of the top half and you can unbolt the fan and take it out. as far as the cooler i would drain and replace its a lot better to do that than laying/sliding around in it when you take it off and try to replace it. but then your truck might not be setup like the coal trucks we worked on. being that its a tractor.

[shortstack]

If the power steering isn't working it probably doesn't have much oil to the cooler although you can't get it all out of the cooler even when you drain the system. Wouldn't hurt to drain it though and put fresh oil in it. Also couldn't tell by your post, the power steering uses dexron fluid but is seperate from the transmission fluid. On the fan, I would replace it because it would probably be out of balance. I do believe the clutch has to come out with the fan. I would try to straighten the shroud best I could and as long as it bolts up and doesn't rub on anything and the fan doesn't hit it, it probably wouldn't hurt anything like it is. Trey

[deercreek]

Thanks alot for your help so far. I didn't realize the power steering/ fluid is seperate from the tranny fluid. It appears like the reservoir is empty so there probably won't be much fluid coming out.

I will probably just have to replace the fan. It seems like it got knocked around when it layed over. It does look like a real pain to replace though and I can't figure out exactly what all needs to come out other than alot of stuff.

[deercreek]

Just had another issue now. When we first got the truck the fan belt was off and the alternator belt was shredded. So we straigtened out the shroud the best we could put the fan belt and another alternator belt on and it wasnt rubbing nearly as bad. Anyway we had the truck running here again and here the alternator belt shredded and the fan belt is starting to come off again. Could this be cause by an out of balance fan and it rubbing against the shroud or is this another issue? Was hoping to drive it 10 miles to our bodyshop to repair the cab but not sure if it would be alright to do that without the drive belts on? We obviously need to get the fan taken care of as well

Edited December 28, 2011 by deercreek

[shortstack]

Hard to say without seeing it but something is either out of alignment or the belt is rubbing on something. Be sure all the accessories (idlers, a/c, etc.) are turning freely. You say it isn't rubbing nearly as bad? It can't be rubbing at all. Trey

[deercreek]

Thanks trey for your help, Does the a/c pulley need to be turning freely, wasn't sure if there is a clutch or something on that? I almost think the a/c pulley wasn't turning freely(will need to double check), I had just assumed that is the way that is but I am probably wrong and that may be the problem of why that belt is shredding. Also if I took it slow and the batteries were fully charged you think I could drive it slowly down the road for about 10 miles? without the belts in place? I would obviously have to watch the tempature etc? I had things lined up for the body guy and now I'm having this other trouble. Thanks so much for your help, Jonathan

[shortstack]

The a/c does have a clutch on the front of the pulley. You should be able to turn the pulley itself easily and you should be able to turn the clutch also but it would have a little more drag. If you have someone helping you, have them get in the cab and turn the key on and then turn the a/c on and off a few times while you watch the clutch. The blower fan switch will have to be on but this should give you an idea of how it works. This is assuming it has freon in the system. If it doesn't, the clutch won't come on. As far as driving it, I wouldn't recommend it because the water pump is also belt driven and the coolant wouldn't be circulated. If the batteries were fully charged it shouldn't have any problem going that far but I don't think I would try it. Can you put the belts on and start it and watch to see if they are rubbing on anything or have you already tried that? Also all the pullies should feel smooth when you turn them by hand. If they feel rough, they could still lock up when they heat up even though you can still turn them. Trey

[deercreek]

I just got done looking over that a/c compressor pulley real good and I think I found the problem. the pulley appears to have been hit by something and put a dent into it. It's not real bad but I don't think its quite turning straight and a few of the grooves at that spot are pushed over just a bit. Thanks for the info on driving it, that was the thing I was worried about. I guess I will just have to buckle down and get a new fan installed and a/c compressor and hope that clears up the problems. One more question, If the fan is out of balance would that mean the clutch is as well or can that thing take a pretty good beating before it messes that up? I just don't want to replace the fan and then here the clutch is bent or something, which I don't think it is.

[shortstack]

If the clutch doesn't look bad, I would just replace the fan and try it. I doubt if the clutch is bad but sometimes you never know. Glad you found the problem on the a/c. Good luck and let us know how it turns out. Trey

[deercreek]

Got good news, got everything back together and the truck runs like a top. Got to drive it around the drive abit and the effort payed off. Thanks so much for all the help.

Edited December 30, 2011 by deercreek

[shortstack]

Good to hear! Now when you get a chance sometime, take some pictures so we can see what you're working on! Trey

[deercreek]

Yes, I will have to do that.

I did have another issue come up when driving it over to the body shop, It would not go over 15 mph its almost like its in limp mode, its obviously the computer that is topping it out. The engine will rev up the whole way when in N etc. It was a very slow ride over there.

The engine light is on and also something that says "dplo" couldn't find anything in the manual relating to that word so not sure what it is? Does somebody know? The other thing I thought of that maybe is putting it in limp mode is because we removed the exhaust pipes(to repair the cab easier), There was a sensor on the one pipe that I had just disconnected, so I'm wondering if maybe that is related somehow. Would sure appreciate any thoughts on this?

Jonathan

Edited December 30, 2011 by deercreek

[shortstack]

That's your problem. It has the regeneration setup on the exhaust and if you disconnect any of it the computer will derate the engine. You will have to reconnect everything and see what it does. I'm not as up to date on the newer computer systems so I don't know if it will run correctly when you hook everything back up or if you will have to take it to a dealer to clear the codes. Someone else on here should know. As far as the light that's on, it isn't pdlo is it? That would be the power divider lockout switch is probably turned on. If that's the case, it's just a matter of turning the switch off. Seems like that switch has a picture of two axles with kind of an X between them. I have a '08 GU713 outside I'll have to go look at later. Trey

[deercreek]

Oh ok, Thanks alot trey for all your help, it has been a great benefit for me. I was just hoping this wasn't going to lead to some major problem but I think you have explained both issues very well and that most likely is the problem. I think maybe you are right, it is pdlo, I couldn't quite remember. It was located right below the electronic malfuntion light on the left hand side of the cluster where all the different symbols are etc. I might have to put on the exhaust system out at the body shop so I can drive it home alittle faster!! Will keep you updated but hopefully everything will fall into place when I reconnect that sensor.

Jonathan

I also added some pictures of the truck below so you can see what for project we got going on. Will have to update it with finished pictures when its done!!

Edited December 31, 2011 by deercreek

[shortstack]

That should make a nice truck when you get it done! I like that under cab muffler setup. Trey

[deercreek]

Would appreciate ya'lls help. Got the truck back together and was planning to get it inspected and have been having some trouble. Am getting this code: MID 128 PID 94

FMI 7 • Mechanical system

not responding

properly

• Drop in fuel

pressure

• Engine derate • Clogged fuel filter

• Faulty fuel pressure sensor

• Leaking fuel line or fitting

• Poor fuel pump response

I had it out in 8 degree weather the first time and it must have almost gelled up so I put some additive thru it and managed to get it back home. Anyway I decided to replace the fuel filters since I was getting this code but the truck is still not working right. It's obviously something with the fuel and it runs kinda rough and then just shut off. We blew out the fuel pump line to make sure there was nothing in there and it appears to be fine. So we are kinda up against. Is there something else that we are missing? The water/fuel seperator sight glass is full, not sure if it's supposed to be empty or full?