1988 Johnson 110 overheat at high rpm

G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
i have recently bought a 1991 19' center console Proline. It has an older 1988 Johnson 110. it overheats at high rpm. with 3 people in the boat it will run 4300 all day long and not overheat, bump it up to anything over 4500 the alarm goes off. I replaced the thermostats and it didnt seem to help. I do not know how old the impeller is but it seems to pump very well, always a steady stream. I will be replacing it soon. I have searched on here for similiar problems , it sounds like it could be the water deflectors. I am going to pull it apart and replace them. Is there anything else i need to do while im in there besides cleaning, scraping, change water deflectors, new head gaskets, water jacket gaskets. is there any modifications i should do?
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,022
Re: 1988 Johnson 110 overheat at high rpm

Nope you have a great plan ;) The deflectors are normally a key item and easy to do (if you don't mind the head gaskets that go along with it).
 
E

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1988 Johnson 110 overheat at high rpm

Since you are going to these lengths to solve the overheat problem, why not pull the head covers off the heads-first? What you find inside the head will also probably be inside the powerhead. It's an easy job-you don't have to pull the heads for this inspection. Is this a saltwater engine?
 
H

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 1988 Johnson 110 overheat at high rpm

Check the big rubber seal, and replace if needed, between the leg and lower unit when you pull it down for impeller change. A leaking seal may allow exhaust to enter the pump.
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

i will pull the head covers first and see what it looks like. but i will have to pull the heads to remove all doubt as to the condition of the water deflectors, thanks for the tip on the exhaust seal, i will replace it also, should i buy oem head gaskets or aftermarket or does it matter? i'm not sure if there were improvements made in the gaskets or not.
 
H

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 1988 Johnson 110 overheat at high rpm

You may use both OEM or Sierra head gaskets, but I've never liked the Sierra paper gaskets, to thin and flimsy. Buy a can of Sealing Compound (Loctite Aviation) as well. Use it on all paper gaskets in connection with water and even on head gasket unless the gasket is marked: Use NO sealer. Even use it on all screws, both head and cover, to lubricate and prevent water to enter the threads. Makes life easier if you have to pull apart later.
Charlie: The deflectors (baffles?) are here at #10:
http://www.marineengine.com/parts/j...rer=Evinrude&section=Cylinder+&+Crankcase
 
C

Charlie in TX

Petty Officer 3rd Class
Joined
Jun 18, 2009
Messages
98
Re: 1988 Johnson 110 overheat at high rpm

Thanks Haff for the reply and a working link.
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
H

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 1988 Johnson 110 overheat at high rpm

Yes, #30. #9 is the water tube, normally not a problem.
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

ok, the water deflectors had definately swelled and closed off the water passage. under the water covers wasnt too bad, we cleaned everything, assembled with new gaskets, plugs, ect. seems to run great ran for like 10 min on muffs, my question is there is two holes right under the cowling directly in the back. is it suppose to have water coming out of both holes? or just one? or either one? the starboard side was spritzing water but didnt see any on the port side. maybe i didnt let it run long enough for the port side thermostat to open ??? i think that is where the thermostat dumps the hot water?
 
H

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 1988 Johnson 110 overheat at high rpm

To get it correct, run in a barrel (water min 3" above split between gearcase and leg) or at sea, but not on muffs.
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

i ran it on muffs tonight to check for leaks before taking it out tomorow, but my question is: is the water suppose to come out of both holes? and is each hole related to each thermostat?
 
H

Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 1988 Johnson 110 overheat at high rpm

Water should come out of each holes as thermostats open and close. Running on muffs, it is quite normal for only one thermostat to work properly due to lack of water and proper circulation and internal pressure. As soon as one opens, pressure is lost to the other.
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

It worked perfect today. Temperature was great. The gauge doesn't have degrees but was almost halfwayin the green which is less than before. Ran 5200 with no problems. And yes water came out if both holes, So the deflectors were definitely the problem.
 
AEROCOOK

AEROCOOK

Master Chief Petty Officer
Joined
Jul 28, 2004
Messages
872
Re: 1988 Johnson 110 overheat at high rpm

Good to hear. I have the same motor so I've been following this post closely. I for one really appreciate it when the original poster gets back and lets everyone know what fixed their problem. There is nothing more frustrating than searching the archives, finding a post that describes your condition only to find that it was left hanging with no resolution. Thanks!!
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

thanks i feel the same way. i ran it all day today with no overheat problems, here is a pic of the deflectors. 1340835518758.jpg,
 
G

Groupergulper

Seaman
Joined
Aug 21, 2009
Messages
73
Re: 1988 Johnson 110 overheat at high rpm

however, it ran with no overheating problems all day BUT we were running at 4800rpm and it just shut off like u turned the key off. i checked everything i could think of, and had the tools for, there was no spark. Soooooo, i will start a new thread about this new issue. :(
 
You must log in or register to reply here.
Top