What did you do with your GMT400 today...or yesterday....

[Big T]

No gasser unless it's dirt cheap

The prices justify my fixing up and painting the ‘94 and ‘99 diesel K2500s.

 

[jrsavoie]

I wish I would have kept the 98 and the 96

 

[Big T]

Installed a new CS-144 250 amp alternator today in the 1994 K2500 Suburban. Old one had given up.

 

[MrMarty51]

Installed a new CS-144 250 amp alternator today in the 1994 K2500 Suburban. Old one had given up.

You did save Your 6.5 diesel pulley ?

 

[Big T]

You did save Your 6.5 diesel pulley ?

I still have the old CS-144. It has the same size pulley as the new one. Also still have the original CS-130 alternator. I can compare the pulley sizes and swap if necessary. What’s the proper size pulley for the 6.5? Where do I take the measurement?

 

[MrMarty51]

Drove the truck to church today.
Total miles since last fuel stop was 96.
33 of that was daily in town driving.
63 highway.
Took 7.0 gals of fuel.
13.7 MPG average
Thats with a new ECM tune from Leroy. Told Him I would like 15 if its dooable and still have power to pull a boat/trailer max 5,000 pounds.

 

[MrMarty51]

I still have the old CS-144. It has the same size pulley as the new one. Also still have the original CS-130 alternator. I can compare the pulley sizes and swap if necessary. What’s the proper size pulley for the 6.5? Where do I take the measurement?

IDR the diameter across the ridges of the 6.5 pulley, It may be 2-5/8ths inch, IIRC.
I recently bought one from Leroy Diesel, I’ll get a measure of it.
I do know that at 70 MPH that the tach is reading just about directly on 2,000 RPMs with 4:11 gearing, or maybe its 4:10, I cant rememer alla this .

 

[Big T]

IDR the diameter across the ridges of the 6.5 pulley, It may be 2-5/8ths inch, IIRC.
I recently bought one from Leroy Diesel, I’ll get a measure of it.
I do know that at 70 MPH that the tach is reading just about directly on 2,000 RPMs with 4:11 gearing, or maybe its 4:10, I cant rememer alla this .

It must be smaller as the tach is reading much higher.

 

[Big T]

OK went out and located the old alternator and measured the OD of the pulley at 65mm. The OD on the alternator I just installed is 60mm. So looks like I need to swap pulleys.

 

[Big T]

I went and swapped pulleys and that was a mistake. I never even removed the cooling fan behind the pulley and now is is scraping on the alternator. Even worse, the lift pump is no longer working. This is a Walbro lift pump and it’s relatively loud. I’m hearing nothing and seeing no pressure on the gauge. I finally got it to start and the fan on the alternator is screeching. I’m letting it cool off before removing to inspect WTF went on.

 

[Big T]

I’m betting the lift pump is a fuse.

The rubbing fan issue is probably due to different configuration of the pulley. One that came off had a spacer built in on the back. The larger one did not. So that had the rim on the larger pulley pushing the fan towards the alternator, causing it to rub.

 

[Big T]

Pics show the differences in the pulleys. Needed to use the spacer behind the larger diesel pulley.

The fan is toast. I swapped in a smaller fan from the CS-130 and will try to separately purchased a new larger CS-144 fan. Got it back to working.

 

[Will L.]

Dag nab it whipper snapper! Sux that happened- but yes the right size pulley is critical for your engine because that alternator is where you get your tachometer. That tells transmission when to play nice and when to play mean.

So lost a alt fan but saved a transmission in time. Letting that thing slip gets costly

 

[MrMarty51]

Spacers is a mighty important factor when swapping components on alternators.
A good rule I go by is after setting the fan to the shaft, hand press the fan towards the alternator housing and see if there is proper clearance.
Less is better as long as it dont rub the housing.