I know this is the Ford forum but...

[Fordsandguns]

I know, I know, this the Ford forum. I posted this in the 6.5 forum too. I'm just trying to help my friend out, any help is definitely appreciated! A friend of mine has a 95 GMC with the 6.5 in it. He just recently bought it. I'm not sure of the mileage. Starts easy, runs fine empty. He has a bumper pull TT that weighs less than 7,000, but he says it won't hit better that 60 on flat road. Less on hills. And it has a lot of clatter now, compared to when he bought it. Any ideas? Also the IP was supposed to have been replaced not long before he got it.

 

[aaklingler]

Replace air and fuel filter. Where is the clatter coming from? Does it smoke?

 

[bigrigdom]

i used to have a 97 1-ton dually with the 6.5 and those numbers sound about right

 

[Fordsandguns]

Replace air and fuel filter. Where is the clatter coming from? Does it smoke?

I'll tell him to do the filters. I havn't heard it but once and that was before the issues. He said no abnormal smoke. Just a lot of black on hills and when he's on the pedal.

 

[JPR]

Is this a turbo 6.5? If so my brother-in-law bought one this summer and it has less power and worse mileage when towing than my truck (see sig).

Two things I noticed was the exhaust is almost as small as the idi non-turbo exhaust and the intake tube between the turbo and intake looks very restrictive. I would start with a decent exhaust and a k&n filter.

 

[Fordsandguns]

Is this a turbo 6.5? If so my brother-in-law bought one this summer and it has less power and worse mileage when towing than my truck (see sig).

Two things I noticed was the exhaust is almost as small as the idi non-turbo exhaust and the intake tube between the turbo and intake looks very restrictive.

Yeah its a turbo. I'd like to help him get it working better if there is something amiss with it. I know the 6.5s were never known for big power but my NA truck will match or beat what he says his is doing.

 

[Diesel JD]

Which is normal. The 6.5 in stock trim made less HP and torque than a 6.9 even though it comes with a turbo. Its not a completely fair comparison since the 6.2and 6.5 were designed with 1/2-1 ton trucks in mind and the 6.9/7.3 are really medium duty motors in a pickup. I would troubleshoot it as if it were a 6.9/7.3 except that the 6.5 also had a PMD computer on the injector pump which was a comon failure point. Apparently it didn't like being subjected to so much heat. Upgraded PMDs are available. I agree, once its fixed...good fuel system, no leaks, no mechanical problems, good timing, its time to make it breathe better. 3" or better free flowing exhaust, better air intake...turn up the fuel mildly and add a pyro.

 

[BigRigTech]

The wastegate on a 6.5 turbo is a poor system as well. If memory serves me right they run about 7psi of boost but I've read that they are famous for popping the wastegate with as little as 3psi with that ***** vacuum operated wastegate actuator. As for the clatter, I would check the lifters. We had one come in a while back with the same noise, found a toasted lifter and a cracked block.

 

[Fordsandguns]

As for the clatter, I would check the lifters. We had one come in a while back with the same noise, found a toasted lifter and a cracked block.[/QUOTE]

Ouch! I hope not! I'm gonna try to go see it today. The fly by wire stuff has me a little intimidated because I haven't ever even looked under the hood of one of these. But how they run is the same as any diesel so...

The wastegate on a 6.5 turbo is a poor system as well. If memory serves me right they run about 7psi of boost but I've read that they are famous for popping the wastegate with as little as 3psi with that ***** vacuum operated wastegate actuator.

Maybe this is why he has lots of smoke with little power? I have already advised him to get a pyro for it so he doesn't toast the pistons. Also I'm gonna tell him to take it and have the codes read on it as was suggested in the 6.5 forum.

 

[Fordsandguns]

Should the wastegate be movable by hand on the 6.5? Running or not on his engine I could move the linkage for it. I found his clatter I think. It sounded like the vacuum pump is making all the extra noise. It takes a while to start doing it after truck is started. Other than that it sounds good. He has had the codes read and one was the electronic switch for the wg. At least that is what he understood they told him it was. It was replaced. I forget the other, but I believe he said it was fixed too.

 

[Agnem]

Timing is going to be just as important to this engine as our IDI. If he feels it has less power than before, I'd check that first, then fuel delivery and airflow.

 

[hesutton]

You might want to check out http://www.heathdiesel.com/ They only deal with 6.5 turbo GM trucks. But, I do like the name!

Heath

 

[Fordsandguns]

Hey, Heath, maybe you ought to start your own heathdiesel and handle only Ford/International! Ok, Matt C on the 6.5 forum explained to me how the wg is controlled by the vacuum. Since the vac pump is in it's death throes we think it is the problem. Not enough vacuum so no boost. Hence the black smoke and no power. My friend (his name is Carlton) is going to run it till the clatter starts, then pull the belt and start it just long enough to make sure it's not clattering, to make sure it is the pump. If no noise without the belt then he'll get another pump and we'll go from there. He isn't trying to make the truck something it's not, he just wants it to handle the hills a little better under load. This is the first 6.5 I've been under the hood on. I like the location of the turbo. It's mounted to the passenger side of the engine. Lot more room on top of the motor than on ours with a turbo. Also, I saw that this thing has a factory version of hydro boost. I haven't ridden in it yet, but I'd like to see how well the brakes work. Do they call it hydro boost or have their own name for it?

 

[Fordsandguns]

The pump was bad, but it wasn't the source of the noise. The harmonic balancer was shot. It was making all the noise.

 

[Matt C]

Hydro-boost is what chevy has called it for many years. It gets it's vaccum from the p.s. pump to run the brakes. Is there now vacuum at the wastegate after changing the vac pump?