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Early Model CH-350 7.4L Crusader - Front Mounted Raw Water Pump Conversion

N

Nightrotor

New member
I have a pair of original CH-350 (454 cid Crusaders) with the belt driven sherwood raw water pumps. The pulley on one pump is badly corroded and I cannot find a replacement. I am interested in converting to the crank or front mounted raw water pumps due to the pulley reason and more importantly to improve maintainability of the pumps. I have read the threads on this, but see a need to consolidate a single thread with the instructions for those of us with these fine engines.


  1. What is the best pump for this use? Are there other options?
  2. What do I need to check on before proceeding?
  3. How do I make sure I have the correct pulleys and harmonic balancer?
  4. How much clearance in front of the engine is required?
  5. Do I really need a bracket for the pump?
  6. What bronze fittings are required?
  7. Are there any modifications to the hose arrangements on the engine side needed?
  8. What are any things to be careful of?

Photos and instructions are welcome, please! Thanks for your help!

Rob
 
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97950 is the 'new' part number for the raw water pump pulley. Its a little bit larger (diameter) so you'll have to get a longer belt.....

Thy also offer a kit if you water to change both belts to the 'newer' setup....unfortunately, the kit isn't complete....and the alternator belt is thinner and they changed the pulley ratios but not by any huge amount....
 
makomark said:
97950 is the 'new' part number for the raw water pump pulley. Its a little bit larger (diameter) so you'll have to get a longer belt.....

Thy also offer a kit if you water to change both belts to the 'newer' setup....unfortunately, the kit isn't complete....and the alternator belt is thinner and they changed the pulley ratios but not by any huge amount....
Click to expand...

Thanks, that is the crank pulley, not the pump pulley. My corrosion problem is on the pump pulley. These are my notes and experience with this:
​

RU22652 BB Pulley Kit - contains DOES NOT WORK Raw Water Pump pulley is misaligned - 3/16" too shallow

1 ea 97952 (GM# 3995647AP) - Raw Water Pump Pulley ( This item has been replaced. Replaced By: CRU-R065047) Not Available
1 ea 97950 - Raw Water Pump Crankshaft pulley
1 ea 97954 - Crankshaft to Alt and circulating water pump​
 
.........................
Nightrotor said:
I have a pair of original CH-350 (454 cid Crusaders) with the belt driven sherwood raw water pumps. The pulley on one pump is badly corroded and I cannot find a replacement. I am interested in converting to the crank or front mounted raw water pumps due to the pulley reason and more importantly to improve maintainability of the pumps. I have read the threads on this, but see a need to consolidate a single thread with the instructions for those of us with these fine engines.


  1. What is the best pump for this use? Are there other options?
  2. What do I need to check on before proceeding?
  3. How do I make sure I have the correct pulleys and harmonic balancer?
  4. How much clearance in front of the engine is required?
  5. Do I really need a bracket for the pump?
  6. What bronze fittings are required?
  7. Are there any modifications to the hose arrangements on the engine side needed?
  8. What are any things to be careful of?

Photos and instructions are welcome, please! Thanks for your help!

Rob
Click to expand...


  1. What is the best pump for this use? Are there other options? I like the simplicity of the Johnson F5B-9 and F6B-9. Sherwood also provides a crankshaft pump.
  2. What do I need to check on before proceeding? Check to see if you have enough space in front of the crankshaft pulley for not only the pump, but to also remove the cover for impeller R&R.
  3. How do I make sure I have the correct pulleys and harmonic balancer? The balancer will be correct. The pulley must have the raised dowels for pump flange indexing and alignment.
  4. How much clearance in front of the engine is required? I should know this dimension but do not........sorry. Perhaps call the supplier and ask for the dimension. FYI... the F5B-9 is the small volume pump (shorter body) .... the F6B-9 is the large volume pump (longer body).
  5. Do I really need a bracket for the pump? It would be recommended..... however, I've been running twin F5B-9s without the torque arms.... no issues to date.
  6. What bronze fittings are required? I'm not following that one!
  7. Are there any modifications to the hose arrangements on the engine side needed? The suction side hoses will need to be collapse proof. The supply side do not!
  8. What are any things to be careful of? two things: 1...... Std LH rotation and Rev RH rotation, of which changes the use of the Inlet/Outlet ports. 2..... Indexing the pump's flange to the crankshaft pulley. Only 1 of the 3 possibilities will be correct.
 

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Nightrotor said:
Thanks, that is the crank pulley, not the pump pulley. My corrosion problem is on the pump pulley. These are my notes and experience with this:
​

RU22652 BB Pulley Kit - contains DOES NOT WORK Raw Water Pump pulley is misaligned - 3/16" too shallow

1 ea 97952 (GM# 3995647AP) - Raw Water Pump Pulley ( This item has been replaced. Replaced By: CRU-R065047) Not Available
1 ea 97950 - Raw Water Pump Crankshaft pulley
1 ea 97954 - Crankshaft to Alt and circulating water pump​
Click to expand...

I stand corrected on the part number error...actually, the 97952 works with the 97950...their offsets (from the original pulley set) is the same. The two big things I don't like about the 22652 set are 1) it isn't complete as you need to change the circulating pump's pulley to match the crank pulley and 2) the resulting alternator belt is much narrower (3/8" vs the 1/2" original).

I don't have any significant time on the new set to tell if the thinner belt is a real issue....with 50 amp alternators, I may just be paranoid...
 
Makomark,

I am not clearon the replacement pulleys. What would need to be purchased to replace the raw water pump pulley and make it work? Does this result in using a different raw water pump belt also?

Rob
 
Rick,

I really appreciate the info and pictures! This will make it easy. I see the raised dowells, but they only appear to be about .100" or less. Is this all there is to them?

Rob
 
Nightrotor said:
Makomark,

I am not clearon the replacement pulleys. What would need to be purchased to replace the raw water pump pulley and make it work? Does this result in using a different raw water pump belt also?

Rob
Click to expand...

I see a few options...if you just want the raw water pump pulley, you could call an OEM like march or spectre and see if they have a direct replacement or a close enough alternative......

You dump a small fortune and migrate to a serpentine belt setup....I've found a couple options but they were all way overpriced for what I wanted.

you could do like what I did and go to all new stuff - with the pulley kit and new belts....

Another option that should work but I haven't verified it would be to get the kit (or the two pulleys for the RWP - whichever is more economical) and just use them with the old circulating pump belt pulleys. i don't see any reason the old alt pulley won't accept the 'newer' raw water pump pulley. as far as belt length goes, with the new RWP pulley pairs, the calculation I did showed a required increase of 1/4"...so I used one of the existing spares.
 
Nightrotor said:
Rick, I really appreciate the info and pictures! This will make it easy. I see the raised dowells, but they only appear to be about .100" or less. Is this all there is to them?

Rob
Click to expand...

Yes, they do not protrude any more than need be for flange contact and indexing.

You could accomplish the same by:
...... making precision bushings for all three mounting bolt bores. Busing OD same as flange bores..... busing ID same as bolt shanks.
..... switch to bolts with more precision shanks that will fit nicely into the bushings.


,
 
All things considered, I think the front mounted pump at about $160.00 is the best option. Thank you for the help. I will be doing this upgrade soon soon.
 
Port engine complete! The only things missing from this thread are the separation of the cast iron pulley and stamped steel pulley and what type of bolts replace the factory pulley mounting bolts. You may need to carefully use a hammer a wood blocks to support the pulley assembly while tappping the cat iron assembly out of the stamped steel pulley. You will need 1 3/4" or 2" GR5 socket head bolts. There is minimal clearance around the bolts and the new pump drive flange which doesn't allow a socket or bow end wrench to get around the bolt head. Use antiseize on the bolts!

Tested for a few minutes at the dock. Solid water flow appearing similar to the old sherwood. Hard run and evaluation to follow.
 
I may not be following you re; the cast iron pulley. Is this an extra pulley that mounts inside of the stamped steel pulley?

As I alluded to earlier, if you do not have the stamped steel pulley with the raised dowels, you can make 3 precision bushings that will center align the pump's flange to the 3 bolt pattern in the harmonic balancer.


.
 
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I don't seem to be able to post photos. The cast iron pulley that drives the raw water pump only is pressed into the center of the stamped steel pulley that drives the coolant pump and alternator. This pulley has the raised "dowells" on it that aligned with the pump holes. I my case it was rusted in place and took a few solid hits with an 18 oz ball peen hammer to free it.

The pump aligned perfectly to the raised dowels and the 3 mounting holes. The bolts are 3/8" - 16 UNC x 1 3/4" or 2". You will need 3 of these with lock washers.
 
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This is the Sherwood E35 belt driven raw water pump we are removing and replacing with a Johnson F6B-9, Model #: 10-24930-01 crank driven raw water pump. The engines are 1986 Crusader 7.4L CH 350, 330 HP. Both are mid 8000s serial numbers. Ignore the oil! I will be fixing that hose next.

Starting Point.jpg



  1. Loosen the alternator and slack off the belt.
  2. Remove the hoses from the raw water pump.
  3. Remove the adjusting bolts under the raw water pump and remove the belt and pump. The bracket cannot be removed unless you remove the coolant pump, so leave it until you have the coolant pump off.
  4. Remove the 3 bolts retaining the crankshaft pulleys. These will come off as what appears to be one pulley.
    • Pulley Assembly.jpg
  5. Separate the stamped steel pulley from the cast iron pulley that drives the raw water pump. Retain this should you desire to return to the hard to maintain original pump! Note the alignment dowels on the pulley.
Pulley and Dowels.jpg​

  1. Fit up the pump over the stamped steel pulley. Note your engine rotation direction and determine which hose will be the inlet. Rotation is determined by looking from the rear, forward.
  2. Use 2" x 3/8"-16 UNC GR5 cap bolts and lock washers with anti-seize to install the pulley and pump.
  3. Tighten bolts to torque spec, if you can!
  4. Install the inlet hose, 1 ¼”, to the strainer.
  5. Run the outlet hose, 1 ¼” to the oil cooler.
    • Partially Mounted Pump.jpg
    • Mounted Pump and Inlet Hose.jpg
  6. Installed and operating. No visible torque movement of the pump when revving the engine.

  • Final Installation.jpg
 
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Judging from how you have plumbed the suction and supply hoses, I assume that this is a REV RH Rotation engine!

attachment.php





If this is a Std LH Rotation engine, your suction and supply hoses are reversed.

crankshaft pump for nightrotor.jpg

My comment re; flipping the pump 180* is optional.


By the way, I would have used socket head cap screws in lieu of the hex head bolts.

None-the-less, you will be glad that you did this.



.
 

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Thanks for all of your help. Easy conversion. Should have done this years ago instead of messing with those expensive and difficult to service sherwoods. The rebuild kit for the E35s cost more than a new Johnson pump. The most time consuming part of this was changing the outlet hose barb on the strainer from 1 3/8" to 1 1/4". I have no idea why the PO had it set up like this, so I took this opportunity to correct it. I will also be putting a tailpipe elbow on it to replace the straight barb and reduce the radius of turn on that hose. Same on the other side. This is the port, reverse rotation or CW, engine. I will be changing to stainless cap bolts (very similar shear and tensile strength to GR5) when I do the other side (CCW or std rotation) in September. The pump will be the same orientation as the engines are identical setups with the oil cooler on the starboard side of the engine. The hoses will be fine with the inlet on top and outlet on the bottom.
 
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