New Melling water pump install -fan clutch question

g00se · Jul 16, 2024

Truck temp was rising a bit at stop lights so I pressure checked the cooling system --and the top weep hole on the water pump was leaking.

Picked up a Melling water pump. When removing the clutch fan from the original water pump, noticed a bit of play then pull/pushing front and back on the non-symetrical 5 blade deep pitch metal fan. Maybe 1/4 inch from one end to the other. How much play is okay? No noise or bearing grind feeling when turning the clutch.

Should I replace this fan clutch?

It has a printed "GM 3J08D2" part number on it --appears to be a severe-duty by the appearance (comparing to other severe vs heavy vs standard). Looking for another factory GM fan clutch but not finding one yet --any suggestions and a good option would be welcome.

Thanks!

someotherguy · Jul 17, 2024

I don't think you'll find an OEM GM severe duty fan clutch new, for your application, at this point. Long obsolete so your chances come down to whether someone has old stock sitting around, which is a long shot. However there are multiple brands for an equivalent clutch.

As to how much play is acceptable, subjective. I'd recommend going to a parts house and have them look up any compatible clutch they have for your truck - doesn't matter standard duty, heavy, severe. Just get a new one in your hand to compare. It does possibly sound like yours has wear, and may be contributing to premature pump wear.

Richard

movietvet · Jul 17, 2024

Agree with @someotherguy. If that fan clutch is original and it is off, replace with new. No brainer.

Lots of choices at RA with several option codes to look at.

g00se · Jul 17, 2024

Thanks guys!
Too bad, I wanted to keep things OEM GM as much as possible. -and the stock clutch doesn't look rebuild friendly for bearing replacement. It isn't leaking or anything..

RA was the first place I looked for a GM fan clutch.

RA has three choices for severe duty --a Hayden, a four seasons and a GMB. Looking closer at the Hayden and it says they make four different types of thermal fan clutches; Standard, Heavy Duty, Severe Duty and Truck Fan Drives. Not sure what the differences are between Severe Duty and Truck Fan drives --unless the Truck-Fan-drives are for larger trucks than a 2500.

Planning on reusing the metal five blade fan so hoping the Severe Duty is the right choice.

Do you guys know the torque spec on the water pump?

someotherguy · Jul 17, 2024

g00se said:
Thanks guys!
Too bad, I wanted to keep things OEM GM as much as possible. -and the stock clutch doesn't look rebuild friendly for bearing replacement. It isn't leaking or anything..

RA was the first place I looked for a GM fan clutch.

RA has three choices for severe duty --a Hayden, a four seasons and a GMB. Looking closer at the Hayden and it says they make four different types of thermal fan clutches; Standard, Heavy Duty, Severe Duty and Truck Fan Drives. Not sure what the differences are between Severe Duty and Truck Fan drives --unless the Truck-Fan-drives are for larger trucks than a 2500.

Planning on reusing the metal five blade fan so hoping the Severe Duty is the right choice.

Do you guys know the torque spec on the water pump?

Double-check to be sure but I'm thinking 22149569 may have been the original # for your clutch? Punch that into the part # search on Rock and see which ones come up. Once you get outside of OEM I tend to distrust what some will list as heavy vs. severe vs. whatever other option. BTW that part # is the ONLY one I can find on GMPartsdirect that references HD cooling of any kind for a 1994 C2500; no mention of "severe" in the list.

Torque specs.. probably listed in the factory service manual, free downloads can be found in the sticky post at the top of the Engines forum.

Richard

g00se · Jul 17, 2024

The fan clutch had GM 3J08D2 printed onto it. No other info on it other than a 'this side down' and a rotational arrow embossed in the casing. Although I haven't yet removed the fan blades so not sure if there is any other possible part number on it.

I did search up RA for the part number 22149569 (thanks for looking that up!) and it came up with the same part options that I found when specifically looking up the 94 5.7 2500 method. --so no actual GM branded clutch fans on RA. I'll probably go with the Hayden one.

The pump is now removed --it was a factory GM embossed branded coolant pump. It had apparently leaked out the bottom side too.

Thanks for the service manual reference.

Coolant Pump bolts --30 ft lbs.

Fan clutch to Coolant Pump stud --18 ft lbs.
Fan to fan clutch bolts --18 ft lbs.

The fan clutch diagnosis section noted that up to 1/4 of lateral movement is allowable. I had just eyeball checked it before removing --so after install the new pump, I'll check/measure it just to see.

"Under various temperature conditions, there is a visible lateral movement at the tip of the fan blade.
Approximately 6.5 mm (1/4 inch) maximum lateral
movement measured at the fan tip is allowable. This is not cause for replacement."

HotWheelsBurban · Jul 17, 2024

g00se said:
The fan clutch had GM 3J08D2 printed onto it. No other info on it other than a 'this side down' and a rotational arrow embossed in the casing. Although I haven't yet removed the fan blades so not sure if there is any other possible part number on it.

I did search up RA for the part number 22149569 (thanks for looking that up!) and it came up with the same part options that I found when specifically looking up the 94 5.7 2500 method. --so no actual GM branded clutch fans on RA. I'll probably go with the Hayden one.

The pump is now removed --it was a factory GM embossed branded coolant pump. It had apparently leaked out the bottom side too.

Thanks for the service manual reference.

Coolant Pump bolts --30 ft lbs.
Fan clutch to Coolant Pump stud --18 ft lbs.
Fan to fan clutch bolts --18 ft lbs.

The fan clutch diagnosis section noted that up to 1/4 of lateral movement is allowable. I had just eyeball checked it before removing --so after install the new pump, I'll check/measure it just to see.

"Under various temperature conditions, there is a visible lateral movement at the tip of the fan blade.
Approximately 6.5 mm (1/4 inch) maximum lateral
movement measured at the fan tip is allowable. This is not cause for replacement."

Be sure to check the back plate bolts on the pump for tightness. I've seen those be loose before, and that's a guaranteed leak.

HotWheelsBurban · Jul 17, 2024

Severe duty clutch probably works with both plastic and metal fans; my Burb has the plastic fan and the crew cab has the metal one. Neither one runs hot...and in Houston summer with the AC on Max, that's saying something.

movietvet · Jul 17, 2024

g00se said:
The fan clutch had GM 3J08D2 printed onto it. No other info on it other than a 'this side down' and a rotational arrow embossed in the casing. Although I haven't yet removed the fan blades so not sure if there is any other possible part number on it.

I did search up RA for the part number 22149569 (thanks for looking that up!) and it came up with the same part options that I found when specifically looking up the 94 5.7 2500 method. --so no actual GM branded clutch fans on RA. I'll probably go with the Hayden one.

The pump is now removed --it was a factory GM embossed branded coolant pump. It had apparently leaked out the bottom side too.

Thanks for the service manual reference.

Coolant Pump bolts --30 ft lbs.
Fan clutch to Coolant Pump stud --18 ft lbs.
Fan to fan clutch bolts --18 ft lbs.

The fan clutch diagnosis section noted that up to 1/4 of lateral movement is allowable. I had just eyeball checked it before removing --so after install the new pump, I'll check/measure it just to see.

"Under various temperature conditions, there is a visible lateral movement at the tip of the fan blade.
Approximately 6.5 mm (1/4 inch) maximum lateral
movement measured at the fan tip is allowable. This is not cause for replacement."

That "3J08D2" number you see is not a GM part #. It is likely a casting number.

g00se · Jul 18, 2024

HotWheelsBurban said:
Be sure to check the back plate bolts on the pump for tightness. I've seen those be loose before, and that's a guaranteed leak.

That's a great tip --unfortunately I already mounted it before seeing it --and could not get a wrench on the now hard to reach bolts. The good news is that I pressure checked for leaks and it looks good, no leaking and held the pressure. The Melling coolant pump (assembled in USA) says that they leak test every unit so I was also putting trust in the good brand name.

With the original fan clutch mounted back on --I wasn't getting much play at all. Maybe 1/8 inch rather than the original 1/4 estimated play. I'm going to give drive it 20ish miles and check it again. If good, I'll check it again after 100ish miles (week) before deciding to replace or not (also keep an eye on the coolant level)

New Melling water pump install -fan clutch question

g00se

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someotherguy

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movietvet

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g00se

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someotherguy

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HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

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