85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

[MI_Thumb_2010]

I recently purchased a 1985 sea ray srv 250 with the merc 260 engine.Had a bellows kit and exhaust shutters installed about a month ago.Ive used the boat 3-4 times after that with no issues.Today i went out and when i was at speed the engine would start to get hot so i slowed to trolling speed and the temp would go back down.I never let it get into the red but it was def headed there.I just kept the rpms low and slowed down when i needed to.Does anybody know what the problem could be?Thanks

 

[cr2k]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

When was the impeller replaced last? A few things it could be are: Impeller, manifolds rusted/corroded, thermostat, obstruction in cooling system. If you have no knowledge of the impeller it is time to start there with a new one, only after you know it is good can you continue (if needed) to diagnose cooling problems.

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Thanks,i will get a new one today and start with that.I will let ya know how it goes.

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Do you have to drain the outdrive oil before taking the lower unit off?

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

To answer my own question yes you do have to drain the oil.Now another stupid question i installed the impeller kit new water pump and housing, impeller etc.I ran it in the driveway on muffs temp gauge went to normal operating temp i noticed at the outdrive where the water exits on both sides of the gimbal housing the right side was WAY hotter than the left side(the exiting water that is)My question is that normal?Thanks

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Bump...Anyone???

 

[achris]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Hello, and sorry I couldn't get to answer your question before this. (I was traveling to work and unable to reach the phone)....

Several possible causes to the problem you have...
1. blockages in the exhaust elbows. And to answer your question about one side being warmer, that's been done to death... EVERYBODY asks that one and they all get the same answer.... It's normal...

2. While you had the lower unit off changing the impeller you should have looked up into the bottom of the upper and checked the water pocket cover.... I have talked about this ad-nauseum over the last few years, and many people do find that they have damaged covers... SO do a search on my username and the words 'water pocket cover'.... I explain what it does, and how to check it out....

Here's a post with EXACTLY the same questions you have, and all have been answered.
http://forums.iboats.com/showthread.php?t=545987&p=3745643&viewfull=1#post3745643
And others with the same advise
http://forums.iboats.com/showthread.php?t=551212&p=3784563&viewfull=1#post3784563
http://forums.iboats.com/showthread.php?t=547166&p=3758173&viewfull=1#post3758173
http://forums.iboats.com/showthread.php?t=551210&p=3784695&viewfull=1#post3784695

Chris.........
P.S. I would also like to add that getting stroppy and posting that other thread hasn't won you any friends. The advise on these forums is free... Many of us work as professional mechanics and this is just a 'hobby' we do in our spare time, not sitting at a computer 24 hours a day. Be more patient and you'll get replies, but bumping after only 12 hours just annoys the people you're asking to help you... you catch more bees with honey than vinegar... Just saying....

 

[FishHog]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

well said achris, and no you don't need to drain your outdrive oil to take the lower unit off.

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Well i appreciate the help and will check the "water pocket cover" but like you i dont have much free time.And to spend hours searching for similar issues is not how i want to spend it.I understand the other thread ruffled some feathers but thats what it was intended to do.

I changed the impeller & water pump housing in outdrive and thermostat in engine but its still overheating.I'll check that water pocket as soon as i have time but when i took the thermostat cover off it was very corroded and full of rust so im thinking the manifolds and risers are prob the same right?I'll order a new manifold kit but will check out your reccomendation before i do so.Thanks for your time.

 

[achris]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

....I understand the other thread ruffled some feathers but that's what it was intended to do.....

If you don't have the time to wait to get FREE information, then take it to the shop, and stop bothering us!

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

EDIT I dont take anything to the shop i'll figure it out one way or the other if i have to replace the entire engine and everything on it.

 

[Bob_VT]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Let's calm down. You have received advice from a pro.

I will strongly suggest adult behavior be exercised. Consider this a warning from the Moderation team.

Thank you achris for your input and efforts.

 

[MI_Thumb_2010]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Well i thought id post what the problem was for people in the future with a similar one.I purchased the boat with the exception the previous owner payed to have a new bellows kit installed to make a long story short it was done at a shop and the water hose that was put in was to long and kinked.Didnt check that at first because i assumed it was new but again another reason i dont take things to a shop.And i changed the water pocket cover even tho it looked to be in good condition and the bolts came out very easy so i guess i got lucky with that.

 

[Thalasso]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

Touchy Touchy. I think if i was asking for free help i would be a little more humble.

 

[tmurphy1602]

Re: 85 Mercruiser 260/350 engine overheating only with high rpms not at idle?

man i learned the hard way they are pros for a reason... lol i Try and not take things to a shop... but sometimes its cheaper and way less stressful... haha well at least you got it man!!