'91 175 XRI Dilemma

91 482v

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Joined
May 21, 2010
Messages
2
Hi Guys,

Got a 175 XRI that was extremely overheated last year. Son had it in the slop and didn't clean the vegetables off the lower unit so when he ran across the lake, the horn was singing away. Figured it was on because of low fuel. 1st mistake was mine for letting him use the boat. That's all water by the keel now anyway.

When I pulled the cowling last year, the nice shiney paint on the heads was a dull grey/black! Temp sensor wiring was melted to heads (both banks). I was SICK!! I just stuck it in the garage adn sulked for several months. This spring, I checked compression and it was 85psi (cold) port-side bottom cylinder runs at 110psi. That's a big difference but could have been from gas/oil in cylinder and sealing it up. I checked compression a couple years back and it sure seems that it was in the 110spi range across the motor. I pulled heads and things look pretty good. Carbon on pistons was maybe .010" thick. No glaring issues with the cylinder walls and they still have a nice cross-hatch on them. The carbon on the heads was even less... in fact, they looked quite impressive for a motor this old! Heads were not warped at all. The "upper" end of cylinders did have a bit of bluing but not bad (maybe a 1/4" from top of cylinder. All were the same so I'm thinking that this was just due to hours of run time.... 375 total. I'm thinking I may just pull "lower" end, push pistons out and re-ring the motor. Isn't a huge deal. What do you think? Any input would be appreciated! Andy
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: '91 175 XRI Dilemma

Before spending the time and effort on a tear down, try using a small fuel tank and follow the Sea-Foam De-Carb procedure, then retest compression.

You can always tear it down after, the pistons & ring lands would be a lot cleaner.

If the heat did not damage the upper cyl's then it may have 'coked' the rings, sticking them somewhat into the ring lands.
 

91 482v

Recruit
Joined
May 21, 2010
Messages
2
Re: '91 175 XRI Dilemma

Thanks for the advice. I'll get some head gaskets and re-install the heads. I do have a small tank set-up for doing my Fall engine conditioning/de-carb process. I've got Mercury engine cleaner too. I'll run it and then do a comp check. The last one was done stone cold on an engine that had been sitting for months without running so I imagine the wall were pretty dry anyway. I'll give this a shot and reply with my results (for others to learn from). Thaanks again for the response.

Andy
 
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