V Belt Replacement Question

G

Glen S

Member
Aug 10, 2009
194
Sarnia, Ontario
Boat Info
Currently boat shopping
Engines
none at the moment
I want to replace the V belts on my 1997 7.4 MPI's. I was at the boat on Sunday and slackened the alternator and idler pulley. But there was very little clearance between the circulating pump pulley and the crank pulley. I figured that I had to remove the water pump pulley and removed all 4 bolts with no issue but the pulley did not seem to want to come off. These pumps are only 18 months old (and we are fresh water) so no corrosion. Is there a trick to removing the pulley. I did not want to start heaving on it or prying it off with a bar without getting some advice. Do I need a puller or special tool?
Thanks in advance for any insight.
 
You may be better off dropping the raw water pump off it's bracket to get the belts off. Removing the pulley screws won't help (as you figured out).

When you re-install the new belts, just remember to put belt closest to the engine (alternator belt) before you put the raw ater pump back on. If you forget, you get to take the pump off and its belt off again. (speaking from stupid experience). The cuss words flowed freely that day.
 
rondds said:
You may be better off dropping the raw water pump off it's bracket to get the belts off. Removing the pulley screws won't help (as you figured out).

When you re-install the new belts, just remember to put belt closest to the engine (alternator belt) before you put the raw ater pump back on. If you forget, you get to take the pump off and its belt off again. (speaking from stupid experience). The cuss words flowed freely that day.
Click to expand...

Rondds,

I am wondering if we have slightly different configerations at the front of our engines. I can't see how removing the raw water pump would increase the space between the circulating pump and crank pullies. I have both belts lossened off and just dangling on the crank pulley - I just can't seem to squeeze them through the gap - those 2 pullies are just too close together.
 
Yes, you need to remove the engine circulating water pump pully to gain clearence to remove the belt.
The four bolts should be all thats holding it on.
I would tap it with a block of wood, maybe the paint is holding it on.
I am 1995 engines but, I think are the same.

Good luck,
Mark.
 
Glen
You have v-drives - I have straight. But the issues should be the same. I have a friend with a '95 370DA with vdrives and he pulls his raw water pumps off every fall and takes them home and it takes him literally 10 min.
 
Thanks for the advice guys.

The boat is stored for winter now. The next time I head down this job is top of the list. Will let you know how I make out.
 
I'am glad this thread was posted as I am in the process of changing the belts , and the raw water pump impeller. I have a 1988 390 with 7.4 streight drives. Yesterday I started to change the belts and found out that the raw water pump belt has to come off first,I thought it should pivot to slacken the belt, just like the gen,but it does not. I had loosen the bolt that runs across to the gen. bracket,no slack ,still a lot of pressure on the belt. I then removed 1 of the 2 bolts that hold the pump to the eng,and loosen the other bolt. STILL NO pivot!. At that point I stopped because the belt was still as tight as it was when I started, then started to removed the other bolt,but was not sure I would get the pump back on and alined with the bolt holes with a new and tighter belt. It looks to me that there is no way to add or reduce pressure on this belt. Am I missing something??....Rip
 
There are two belts on your motor, both can be adjusted.
One via the alt. is on an adjustable bracket and the other via the idler pullly.

The clearence problem talked about on this thread is the engine water pump (not raw water) pully has to come off to get the belt off.
Strange but, Merc. made it like that....

Cheers,
Mark.
 
What I do is just take the long arm that extends from your raw water pump over to the engine OFF the engine and drop the pump to the bilge floor. That should do it. If you are looking at the front of the motor, on the right side is a place where the alternator adjustment arm bolts to the motor,which is also where the raw water pump bolts - I think it's the same hole. Take that bolt out along with the two you took off (the ones that hold the pump assembly to the motor) and the whole pump will fall away from the motor. Now you can maneuver it to get the belt off. Just remember to put that belt back on before you put the alternator belt on. IF you forget, you're taking it all off again.
 
Thanks for the reply,I was on the right trail going to do the belts, and impellers also thermostats. Everything in fla is perfect for cruising I need to finish up and get going...Rip
 
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