Mercruiser I-Drive 888 Raw Water Pump Questions

[Apollo75]

I would like to ask a few question about the Mercruiser 888 -- 1975 vintage serial number beginning with 42.....

I have had this boat for many years but others did the work on the outdrive. I removed the lower unit to replace the raw water pump impeller, install new prop, check things. I placed shifter in forward gear, drained gear lube, removed prop, removed lower unit.

No water in lube, lube looked good, no metal. I noticed the gaskets on the drain and vent screws were not reusable, also there is a O-ring that seals the lube passage between the upper and lower units (I did not know about). The drive shaft upper O-ring came off the shaft and was in the upper unit passage --- fished it out with my finger. Does this O-ring normally seal tight in the upper shaft grove ? This one is loose.

The pump was black and did not have seals in the upper housing just the slinger rubber on top. Manual says newer units do not use oil seals ?

At what serial number range did the change occur for no oil seals --- does it matter ? --- all the pumps for the older units I have seen have been a white color --- does it matter ?

I have heard about using a magnetic drain screws ---- sierra part is for MR/Alpha 1 says do not use on older units --- is there a clearance issue ?

The old impeller has a set and blades are cupped (worn in the center) --- insert cup has only very fine marks for wear --- will new drain and vent screw gaskets and impeller replacement be fine ? Or, should I order a new pump with upper and lower housing that has all the O-rings and gaskets ?

The impeller moves quite a bit with the old key --- new key ?

Purchased impeller only.

Quicksilver High Performance gear lube says not to mix with any other gear lube (read after I got home with my reading glasses on) -- also bought AMSOIL synthetic Marine Gear Lube --- can I mix, top off with AMSOIL --- does it matter ?

Service lower end --- New pump unit 2-years ago.

Thank you for your kind attention

OFM

 

[ziggy]

Re: Mercruiser I-Drive 888 Raw Water Pump Questions

Does this O-ring normally seal tight in the upper shaft grove ?

not sure where it rides. but for sure. that oring is obsolete. you can leave it off. proof would be that in the later version of the 1 drive the oring slot was eliminated. no where to put the oring.

At what serial number range did the change occur for no oil seals --- does it matter ?

it don't matter. year after year i've gone w/o the oil seal that was at the top of the water pump housing. i have the same drive ya got, but for a 165hp L6.

I have heard about using a magnetic drain screws ---- sierra part is for MR/Alpha 1 says do not use on older units --- is there a clearance issue ?

yes. can't remember who, but someone put one in there 1 drive the other day here. broke off the magnet and crushed it up. a magnet all crushed up mixing with the gears... he had/has a real issue that needs addressed.. bummer.

will new drain and vent screw gaskets and impeller replacement be fine ? Or, should I order a new pump with upper and lower housing that has all the O-rings and gaskets ?

up to you. do you know the history of the housing? grooves would be bad. have ya had cooling issues? i've replaced mine for piece of mind + now i know how old it is and the kind of use/abuse i've givin it.

The impeller moves quite a bit with the old key --- new key ?

the kit comes with one. replace it. if ya go with the impeller only. your call. can ya get one. all it has to do is lock the impeller in place. is it worn? replace it...

Quicksilver High Performance gear lube says not to mix with any other gear lube (read after I got home with my reading glasses on) -- also bought AMSOIL synthetic Marine Gear Lube --- can I mix, top off with AMSOIL --- does it matter ?

don't mix. use one or the other. i use the mercruiser high performance. best i understand it'll mix with water but still lub, a little. better than separating as water don't lub. but still. don't mix one lub with another. specially if the bottle says don't... i'd guess they've got a reason to note that..

Service lower end --- New pump unit 2-years ago.

that's the outside edge of service for a 1 drive impeller i think. they seem fragile to me. mercruiser calls for inspection once a year. since they're hard to go look at, i replace it on general principles. a good impeller is most critical for proper cooling. everything depends on it. i feel it's just good insurance to R&R it yearly..

oh, the color of the water pump housing don't matter. mercruiser is black. i think serria is white. i like oem parts. they seem to work best... good luck..

 

[Apollo75]

Re: Mercruiser I-Drive 888 Raw Water Pump Questions

Most kind ZIGGY

The problem is I have never seen the inside of one and cannot tell if some of this is normal or not. If they gave me specifications as to size and wear (something I could mic) I would fair much better.

The AMSOIL says it still works "even when contaminated with 10% water." Tempting

OFM

_______________________________________
"If the boat is not sinking or on fire ---- Relax."

 

[jtybt]

Re: Mercruiser I-Drive 888 Raw Water Pump Questions

I agree with everything Ziggy said except I would stress to replace the pump housing with the impeller. Just get the whole pump replacement kit.

The pump has a seal in the lower housing so the 'slinger' is all that's needed at the top of the housing.

 

[Apollo75]

Re: Mercruiser I-Drive 888 Raw Water Pump Questions

Thank you for the advice fellas. I used the Quicksilver High Performance gear lube ---- pretty color --- it is not what was in it --- I did let all the old lube drain out and drip a few minutes before refilling the out-drive. I will check and see if the new High Performance lube increases my top speed and get the vital information back to you all.

I read about everyone saying it it a quick, and easy job --- I had no issues except the temp has slowly risen since the pump replacement at low rpm --- so I bought just an impeller --- thinking a new pump was installed 2-years ago, few hours, low wear --- I didn't know about the oil passage seal, etc. or I would have ordered the whole pump. I will get a new complete pump on my next on-line order.

It was quick and easy with all your help

OFM

______________________________________
"If the boat is not sinking or on fire ---- Relax."