Engine Overheating when trimming out?

[NelsonQ]

Ok...let me first say I'm posting this for a friend and I know NOTHING about I/O.

He has a 4.3L Mercruiser (carbed) with Alpha I outdrive.

He purchased it with a 30 day warranty from a private seller. During that period, he sent it to a marina for an inspection and it all checked out great.

When my friend picked it up, they were having problems with the tilt/trim which they resolved but.....

Yesterday we dropped it in the lake. Runs like a champ, temp is normal with the outdrive trimmed all the way down. As soon as you trim it up 1/4 to 1/2 ways, the temp runs hot in about 10 secs and off goes the heat sensor alarm.

Trim it back down, put it in gear, and within seconds, the temp is normal again.

My though is something is restricted when trimming up (intake appears fine so I assume its on the return.) I know this is probably simple for you I/O guys.

IF you have any thoughts, I'm heading back tomorrow to the lake. Any suggestions appreciated.

Also, it will be going back to the marina but they're closed until Tues. Other interesting part as well is now when we turn the engine off, it stumbles for 3-5 seconds (I assume a timing issue, but the marina can have that problem)

 

[EddiePetty]

Re: Engine Overheating when trimming out?

...supply hose from the lower unit to the transom shield is kinking when triming out.

 

[NelsonQ]

Re: Engine Overheating when trimming out?

...supply hose from the lower unit to the transom shield is kinking when triming out.

Thanks.... is that something you have to drop the outdrive to fix?

 

[EddiePetty]

Re: Engine Overheating when trimming out?

Thanks.... is that something you have to drop the outdrive to fix?

......wellllll....

With the bow down, the outdrive up and straight ahead, you have itty-bitty hands and the patience of a saint, you might be able to do it with the drive directly in your way !!!

If you're fumble-fingered, have bearpaws, six thumbs and no patience: just pull the drive (eight nuts and a yank)

 

[Don S]

Re: Engine Overheating when trimming out?

If that hose is kinked, you will need a new hose, and yes you will have to pull the drive and the bellhousing to get to it.

 

[NelsonQ]

Re: Engine Overheating when trimming out?

......wellllll....

With the bow down, the outdrive up and straight ahead, you have itty-bitty hands and the patience of a saint, you might be able to do it with the drive directly in your way !!!

If you're fumble-fingered, have bearpaws, six thumbs and no patience: just pull the drive (eight nuts and a yank)

Thanks, and your mention of patience just removed that option for me

 

[NelsonQ]

Re: Engine Overheating when trimming out?

If that hose is kinked, you will need a new hose, and yes you will have to pull the drive and the bellhousing to get to it.

Thanks DonS. As I mentioned the marina dropped the drive and had the whole thing apart. With the $600+ bill for minor repairs and inspection, they'll be doing the work/hose replacement since that only happened after they had the outdrive off.

 

[NelsonQ]

Re: Engine Overheating when trimming out?

So latest update is it made it to the marina to look at it and they said the don`t see any kink/bend in the hose and the problem is most likely the impeller.

So my question (which I believe the answer I already know) is why in the heck would at 4600RPMs with the trim all the way down, would the impeller supply enough water flow to cool the engine, but at partial way up, at any RPM, its starts to overheat?

Seems to me the impeller is doing its job but changing it since it was just bought used is a good thing.

Thoughts or is this a possibility? (makes you wonder what was looked at in the thorough inspection if they didn't look at the impeller. Seems like a basic check/replace starting point)

 

[EddiePetty]

Re: Engine Overheating when trimming out?

........So my question (which I believe the answer I already know) is why in the heck would at 4600RPMs with the trim all the way down, would the impeller supply enough water flow to cool the engine, but at partial way up, at any RPM, its starts to overheat?........

Seems to me the impeller is doing its job.........

....and I agree, the impeller does seem to be doing its job.

Other than the supply hose kinking, the only other suggestion I have is to check that the inlet port(s) are not being partially exposed due to degree of trim or water deflection from a trim tab, transducer or speedo-pilot.