powerhead swap

[rpnlps]

i bought a bass boat from a guy,but there was no where to test the engine where he lived.long story short it had three siezed cylinders.it is a 1990 johnson gt 175. i talked to a guy on craigs list who said he had a 1991 200 johnson powerhead that had one bad cylinder and would be no problem to rebuild.i got it here,its rebuildable allright but the exhaust housing on the back of the motor is cast into the block where mine on the 175 is bolted on.he says that shouldnt matter.they are both bubble back exhaust housings.they both have one piece heads ,doesnt that make them both loopers?the bolt pattern also looks different on the base of the 200.PLEASE HELP I NEED TO GET BACK ON THE WATER ...THANKS SCOTT...ps do i just need to replace the mid section?one more thing.the pistons on the 1990 are domed top,the 1991 are like flat tops if this helps..

 

[cdoliver]

Re: powerhead swap

your 1990, is a crossflow, your 1991 is a looper. they do not interchange to my knowledge. If I'm wrong someone correct me...

 

[daselbee]

Re: powerhead swap

First of all, we don't know any model numbers of the two engines in question, so everything we say is speculation at this point.
Get the model numbers and:

You can look up parts diagrams and compare part numbers on shop.evinrude.com. Pay particular attention to the gasket part numbers. If the two engines use the same P/N gaskets at the same location...it gives you more insight as to whether they will swap.
And yes, the 175 is a crossflow, and the 200 is a looper.

I will stick my neck out and suggest that you MAY be able to do the swap at the bottom of the exhaust adapter. This would be the joint between the midsection and the exhaust adapter. The two may be the same at that point.
You gotta consider also the cowlings and engine cover.
I know for a fact that the 200 is a 90* looper. The 175 may be a 60* engine, which is narrower, and the covers would not fit.

 

[Faztbullet]

Re: powerhead swap

Wont work, the last year crossflow was a 1991. No parts off the 175 will fit the 200hp looper except maybe the stator. You can find the 150hp on craigslist as these are a dime a dozen and cheeeeep!!! and these are better than the 175 big bores in my opinion as the 175 BB sleeves are to thin.

Heres a a mid 80's that will fit for $300. http://nashville.craigslist.org/boa/1101666379.html and one that runs for $200. http://nashville.craigslist.org/boa/1098329264.html

 

[daselbee]

Re: powerhead swap

Whatch gonna do with the blown 200 looper p'head?

 

[wesley pipes]

Re: powerhead swap

yea you have 2 diff powerheads on your hand my best bet is sell em both and get a used one.