Fan Gearbox - Don't Forget to Service

[truk4u]

This is probably one of those maintenance items that is routinely forgotten or overlooked. The manual says to change the oil every 50K, wonder how many have actually been done.

In case you haven't done it, there is a plug on the left side that drains the oil and a plug on the right side that is the level indicator. After draining, just fill until oil starts to come out the level plug. Check the vent tube also to make sure it can breath.

At the very least, check it for oil.

8333

[kenrobertson]

Thanks Tom - In my limited experience, this gear box is one of the most frequently overlooked service items on our coaches.

[phorner]

Interesting..... mine has a dipstick.

Although I regularly check the level, I've yet to change the oil. Bet it's never been done and it's now on my to do list.

[truk4u]

Ken - Your limited experience!:rolleyes: You forgot more than many will know...

Paul - You lucky dog, mine was kind of designed like my bush hog. Fill it until it runs out the hole.:p

[Ledo]

Mine also has a dipstick and I doubt it has ever been changed in its 100K life either. What is the weight of that gearbox oil?

[truk4u]

75 or 85 Synthetic according to Prevost. The manual recommended Mobil something so I called and they said any Synthetic will do.

[stevet903]

Mobil SHC 630 is what is currently recommended - see http://prevostparts.volvo.com/technicalpublications/pdf/MI99-08.pdf

PN 18217 from Prevost is $60. Graingers has the same quart size (all you need) for $20

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=SHC+630&op=search&Ntt=SHC+630&N=0&sst=subset

I'd say that you could use Delvac Synthetic gear oil 75W-90 which I have bought before at TA Truck stops

http://www.imperialoil.ca/Canada-English/Files/Products_Lubes/IOCAENCVLMOMobil_Delvac_Syn_GO.pdf

[srowe]

Just finished replacing the original gearbox with the Boston Gear unit. It came as a kit from Prevost. It came with a dipstick but the is no clearance for it. The box is VERY close to the exhaust flex pipe (8V92). Anyone else have experience with this?

Steve Rowe
90 Royale XL

[Jon Wehrenberg]

Is your set up standard Prevost or has it been modified?

My 8V92 1987 model had the gear box out in the open behind the rear doors and the exhaust from the turbo was well to the rear. Nothing was placed above the gear box. FWIW on early Prevost chassis the original fan had metal blades and was very heavy. A retrofit fan with nylon or fiberglass blades which was much lighter was offered to save wear and tear on the gear box.

[BoaterAl]

Speaking of fan blades........
I had a tenant at our diesel pusher only storage several years back. Owning a mid 90's Prevost he hired a crackerjack mechanic to change out his engine cooling fan from metal to nylon or fiberglass. The lighter weight thus better fuel mileage. Makes sense to me. Orders fan, finds mechanic ....…What could go wrong with this simple job ????
First off the replacement does not match up to bolt pattern so that needs to be exchanged. With the now correct fan ( 2 weeks) received the new one is ready to be mounted in place. Waits again for mechanic now working on another part time job, another 2 weeks.
All set for better mileage, and stocked for a vacation, family, dog, kids off he goes... sort of..... overheating about 5 miles from the bus barn. Turns out the blade angle was reversed from his original metal fan blade. Of course the blame game was in full mode by the crackerjack mechanic who for some reason (lazy comes to mind) never laid the original with the replacement side by side and refused to do the job again without being paid before hand. How things can go landslide wrong.

[stevet903]

Steve - Mine is the same way, I thought maybe you could rotate the cover and move the dipstick but that didn't work on mine... As long as it's not leaking you don't need the dipstick!!

[srowe]

I think my setup is original to the coach but my exhaust off the turbo angles down toward to front of the engine compartment, right over the gearbox. Seems like a bad idea to put all that heat so close to the gearbox. Replaced the muffler while I had space to do it from the top too and believe it was original to the coach as well. Mine still has the heavy steel fan and after learning just how much it weighs, that fan upgrade sounds like a great idea. Looking at the parts manual it looks to be a fairly simple hub change on the gearbox to do the changeout.

Good point on the dipstick. I can often be counted on to overlook the obvious.

Steve Rowe
90 Royale XL

[Garynmike]

I was looking at that and wondering.... now I know the oil should be drained and replaced!

[Joe Camper]

If u don't see a rebuild in the service records u need to get it apart and rebuilt not just serviced.

Take the belt off and check for play in the shaft. Look see if there is a ring dancing around on the shaft between the back of the pully and the case indicating the outer bearing close to death.

U should see a grease fitting on yours and the service intervals for it is daily.