Logo
FULL SITE MENU

Volvo AQ250's interchangable w/ 270's?

G

Gibson36

New member
Hi all. New member here. I've got a 36' Gibson powered by 2 Chry M273's with 2 AQ 250 sterndrives. One of them has part #PZNR2523315B (the other ends in B as well. My question is if I wanted to replace them, it seems AQ 270's and AQ 280's are easier to locate. Can I just "plug in" two 270's or 280's. How interchangable are these sterndrives? Any help would be much appreciated!
 
Gibson36 said:
Hi all. New member here. I've got a 36' Gibson powered by 2 Chry M273's with 2 AQ 250 sterndrives. One of them has part #PZNR2523315B (the other ends in B as well. My question is if I wanted to replace them, it seems AQ 270's and AQ 280's are easier to locate. Can I just "plug in" two 270's or 280's. How interchangable are these sterndrives? Any help would be much appreciated!
Click to expand...
The 250's are know as "small bearing" units! This means that a 250 transmission ONLY fits this Intermediate housing.... you cannot install a later transmission on this Intermediate. (has to do with the OD of the driven gear bearing and retainer)

So..... if you were to change to a 270, 275, 280, you would need to also change Intermediate housings.
Anytime we change a transmission to another Intermediate, we MUST re-calculate the shim value between the driven gear bearing and the Intermediate housing bore.
Simple to do.... but must be done!

Likewise when changing a lower unit to another Intermediate housing.

Now..... if you are asking if an entire 270/280 drive can be swapped.... the answer is YES.
It can be done so long as you stay with the same over-all gear ratio that is correct for your engines!
The 250 "Main Suspension" forks are the same dimensionally.
The Rev Latch is in the same location, push rod is same, etc.

NOTE: the 250 suspension fork has an insert in it for the rev latch unit....., making it a slightly weaker fork!
The 250 universal shaft "male yoke" is smaller in diameter, also making it a slightly weaker component.
Lower unit gears are bevel cut.... making this a wee bit louder operating gear set. Usually a non issue as they are very bullet proof!

All else is pretty darn tuff!


What are your issues with the 250's?


.
 
Well I had some electrical problems last summer and the part of the drives in the water got some galvanic corrosion. I think they may be fine but they look bad till I get them sanded down and painted. I just drained one of them yesterday and could not see any filings and there was no water. I'm in the process of selling the boat and want to be able to tell people that 270's or 280's would work. First guy that looked at it walked away cause of difficulty finding parts for the 250's. The 270's and 280's seem to be more abundant when I search the internet. One other question... if I did replace them do I need to worry about direction of rotation or can that be addressed by just hooking up the shift lever in the other hole? Thanks for the help Ricardo!
 
Well, as for the question regarding parts availability.... here is what you do then:

**You have either a 270 or a 280 Transmissions AND Intermediate housing ready to go. So there's your 250 upper replacement!

**Since any of the V-8's w/ a 250 drive were single exhaust relief transom shields, any single relief transom shield will work! They are practically a dime a dozen since they do not work for the later V-8's.

**Since ALL lower units interchange.... there is NO issue there. Only the shimming of the vertical shaft tapered roller bearing race!


You are correct on the rotation! That is one of the beauties of the old AQ series V/P drives!

.
 
Last edited:
I did this exact swap on my Lancer. P/O had damaged the 250 drive and replaced it with one with the incorrect ratio, so I had to find a drive with the correct ratio. I located a 280 leg, and the swap was a no-brainer. One issue would be to not use an exhaust bellows with built in flapper and use a flapper on the 280's external exhaust port. Since this part, if missing or damaged, is not available (so I"ve heard), it's been suggested that this almost same part from a 290 drive will work with minor fiddling.
 
Bob, that is true and I agree.... I don't want a flapper inside of the exhaust bellows on any V-8. It's just too restrictive!
A 290 exhaust outlet flapper can be retro-fit to a 280, since a 280 exhaust outlet flapper was never offered over the counter (it was a production model only).


.
 
Thanks you guys. The exhaust bellows I just relpaced last year did not have a flapper. I am missing one flapper on one exhaust outlet. Is this a big deal. I never understood what function they provided since my exhaust manifolds are so high above the water line.
 
Sometimes all it takes is one large surge wave from a passing vessel to force water up and into your exhaust system and into an open exhaust port.

Your call!
 
Gibson36 said:
Thanks you guys. The exhaust bellows I just relpaced last year did not have a flapper. I am missing one flapper on one exhaust outlet. Is this a big deal. I never understood what function they provided since my exhaust manifolds are so high above the water line.
Click to expand...

I always wondered about that too. What I'm guessing is maybe it acts as a coolant or to prevent dirt ?? not sure. If it's there, it's there for a purpose but this time I'll surely try to find out.
 
Back
Top