1990 Evinrude 140 overheating

[paul99]

I've been having problems with this motor overheating on the STBD side only (after lots of testing and checks) for a while at 3800rpm and above. The t/stats are good so are the sensors each one operates at the proper temp by the manual. Someone posted earlier that the deflectors may be the problem. I did a compression check before pulling the heads. (engine warm and throttle wide open) cyl # 1 was 110 all others were 122 - 125. So it looks like I have someting wrong on both sides of the engine.

The heads are off and #1 cyl has some scoring. Is this worth just working on this cyl and honing lightly and re-ringing? Also I did not find deflectors in the block on either bank??? The manual says they should be there but they are not. Does anyone know for sure if this block is supposed to have them?

 

[HighTrim]

Re: 1990 Evinrude 140 overheating

I do believe those deflectors should be there.

Picture compliments of Ezeke.

 

[ezeke]

Re: 1990 Evinrude 140 overheating

Edit, see next.

 

[ezeke]

Re: 1990 Evinrude 140 overheating

No deflectors on big bore loopers. Look elsewhere.

Take the thermostats out and check the seats.

 

[paul99]

Re: 1990 Evinrude 140 overheating

Did that. The plastic housing is cone shaped and it seats on the rubber ring in the head. I blew through it a little so I took it apart and the veratherm was a little rough were it seated in the plastic housing. Could this leak by prevent them from unseating at high rpm operation? I bought new ones and you can't really blow through these as easy. I have not had a chance to try them since I'm waiting on the head gaskets to arrive. Thanks all.

 

[ezeke]

Re: 1990 Evinrude 140 overheating

I replace those as a unit, using thermostat assembly, part # 434137. Also, be sure that the little hole in the thermostat cover diaphragm is open and the slot opening below it is free of material.

 

[reeldutch]

Re: 1990 Evinrude 140 overheating

get rid of that termostat system and use the 1993 tstat system of thge suffix "s" model.

get the tstats the springs the covers and your good to go.

specialy a better system if you are in saltwater.

 

[paul99]

Re: 1990 Evinrude 140 overheating

ezeke and reeldutch, Thanks for the replies.

The new t/stats are the whole assy as you suggested. Someone sent me an e-mail to say "this engine originally had power boost cooling and you need to verify if it is still being used or you can update to newer style thermostat covers and remove powerboost cooling".

This is first time I heard of this. Does anyone know what this is and how to identify it? reeldutch what hp 93 engine do I need the parts from to fix this?

What about the scoring in cylinder 1? Any ideas.

 

[ezeke]

Re: 1990 Evinrude 140 overheating

Is there any way that you could post some pictures showing the scoring? If you have a bad ring, you need to tear the engine down and replace it or your damage will just get worse.

The later replacement covers for the thermostats will not have hose outlets. Part numbers will be 333967.

The later covers do not use the diaphragm, they use a gasket # 329830 instead.

You will need large springs, part #336765 or 0333858.

You should use the new thermostat assemblies, part # 434137.

You will need to re-route the tell-tale hose.

Keep the old thermostat housing if they are the white ones. The extended noses will fit the new assemblies and they provide better circulation. If you find that you have a marginal cooling problem, you can just switch the noses and get more water through the cooling passages.

Test the old vernatherms. If they are still functioning, keep them for spares.

 

[paul99]

Re: 1990 Evinrude 140 overheating

Thanks for the part numbers. I'll get these ordered. The scoring is worse than I think normal "light" honing can fix. I'm going to take it to my local shop and have then give it look see etc. The cooling system upgrade should fix this. I appreciate all the feedback. While I'm at it I'll replace the pump assy to get a good baseline. Thanks again.