Evinrude 235 overheating

[keysrat]

I have a 1982 Evinrude 235 that is overheating. I have changed the t-stats and the waterpump impeller, not the housing. My water presser is 5psi at idle to 30+ WOT. Because my pressure seems to be good I do not believe I have a clog. Both the port and starboard cylinders are roughly the same temp hot to the touch. The alarm goes off after running the engin for about 5 to 10 minutes at over 3500 rpms. On the hose the engine does not overheat and the temp in the drive way is around 145 degrees. All the cylinders are within 3 degrees of each other. When I remove the t-stat cover steam or smoke comes out but I can not tell which it is, could I be getting exhaust in the cooling system? The exhaust housing seal around the lower unit is worn. The gormets are also a little worn. <br />Thanks, <br />I’m back

 

[Walker]

Re: Evinrude 235 overheating

Could be the water deflectors in cylinder jackets. Could be salt/calcium/corrosion build-up inside your water passages. That will insulate the metal and inhibit heat exchange. They sell a flush concoction. I think West Marine handles it.

 

[keysrat]

Re: Evinrude 235 overheating

I'll be going downtown on Tuesday so I will pick some up and give it a try.<br />Thanks,

 

[Dhadley]

Re: Evinrude 235 overheating

As the deflectors get old they "pooch" out. Just like me. They can go from deflecting the water to obstructing the flow. Might not hurt to replace them. Standard part of a cooling system service.

 

[angus63]

Re: Evinrude 235 overheating

Since all of the cyls are similar in temp, I'm leaning towards an overall system restriction or calcification. Doin' a flush is a lot easier than breakin' down the motor. I'd opt for the system flush first. Have you tried running without the t stats to rule them out?

 

[keysrat]

Re: Evinrude 235 overheating

I have run the engine on two different sets of t-stats one set with a notch. I thought if you ran the engine with out t-stats the water just runs through the system with out picking up the heat? I might just go through the system for fun then flush with some cleaner stuff While the engine is opened up I would not mind looking around a bit <br />If it's not one thing it's another! I don't mind as long as its cheap

 

[angus63]

Re: Evinrude 235 overheating

T stats lessen the time it takes to get to operating temp by restricting flow. Under a load with moderate intake water temps, the motor will reach it's operating temp with or without. Stats also maintain operating temp during prolonged idling. If you do not hear the warning tone after 20 min at cruise without the stats, I would double check you have the correct ones installed correctly with the correct venting.<br />Good luck

 

[keysrat]

Re: Evinrude 235 overheating

Ok, I will check the stats again this weekend before cleaning out the system. I do have the correct stats. What do you mean by correct venting?<br />Thanks for the help and I will post back the outcome this weekend.

 

[keysrat]

Re: Evinrude 235 overheating

I got a chance to check out the engine today and the cooling system is dirty. There was rust, salt, plastic and other build up in side. The deflectors were also mushed pretty bad. Is there a bolt pattern I should follow for the cylinder heads? What should I torque the bolts too 30 fp? What is the operating temp for this engine around 160 degrees?<br />Thanks,

 

[angus63]

Re: Evinrude 235 overheating

For bolt pattern, I work from the center of the head and alternate sides working outward. Need to check manual for torque, but I believe it's more in the 20-24 ft-lb range (please check manual!). Since the water temps down in the Keys is relatively high (probably the warmest in the US), I would estimate anything shy of 170° F would be ok. More importantly, watch for temp spikes and be sure horn is working.<br />Good luck

 

[keysrat]

Re: Evinrude 235 overheating

Luckily the horn's working The horn went off, I looked at the temp gauge and slowed down then let idle for a moment before I shut her off. The water temp right now is around 72f in the summer it will get into the mid 80's easilyUnfortunalty I am still waiting for the manual to arrive. I agree with you, the torque is probably around 23ft-lb, thinking about it 30 seems like it would be too tight. Hopfuly someone on the board will know <br />Thanks,

 

[Dhadley]

Re: Evinrude 235 overheating

Torque the heads to 18 ft lbs. Then retorque after the motor has went thru a few heat cycles.

 

[keysrat]

Re: Evinrude 235 overheating

What should I retorque them too after the heat cycles. What do you mean by a few heat cycles? <br />Thanks,

 

[Solittle]

Re: Evinrude 235 overheating

A heat cycle is when you bring it up to operating temp as in going out for a run and cooling down when you get back. Retorque to the same value. It may not take any or just a pound or two.

 

[keysrat]

Re: Evinrude 235 overheating

I have it back togather. All the deflectors looked real bad. One of them was completly closed in. I am going to run some of that anti-salt stuff through it and will recheck the torque after that and after running her. I will post back the results when I have them. I'm hopeing for the best. <br />Thanks to everyone

 

[walleyehed]

Re: Evinrude 235 overheating

Keysrat, if you have a manual, please note the location of the deflectors....I know you already have it together, but if you still have problems, make sure they are in the correct location. If the 235 has bypass water valves next to the T-stats, I can see possible issues there in salt conditions. Good luck.

 

[seahorse5]

Re: Evinrude 235 overheating

Originally posted by keysrat:<br /> I have it back togather. All the deflectors looked real bad. One of them was completly closed in. I am going to run some of that anti-salt stuff through it and will recheck the torque after that and after running her. I will post back the results when I have them. I'm hopeing for the best. <br />Thanks to everyone

A common saltwater problem with high speed overheating in saltwater is debris, salt, and sand buildup between the cylinderheads and their water covers. The buildup restricts the hot water coming out of the thermostats and pressure relief valves causing the motor to run too hot. You have to remove the covers and scrape out the deposits. On that old a motor, there will probably be a lot of salt encrusted in the nooks and crannies of the head and cover.

 

[keysrat]

Re: Evinrude 235 overheating

I hope I put the deflectors back in the right spot. There seemed to be a grove where the deflectors slide into. I just put them where the old ones were in that grove. Just below the t-stats is a plastic and rubber valve. When I took off the cylinder head there was lots of debris of all different sorts in there. I did a lot of scraping on both the head and around the cylinders. The spaces and the water passage between the cylinders were dirty and I scraped them out. What are the water covers and how do I remove them? <br />Thanks,

 

[Walker]

Re: Evinrude 235 overheating

The covers are on the heads, but you're probably gonna break off about 14 bolts trying to get them out.

 

[keysrat]

Re: Evinrude 235 overheating

So the covers are the thin peices of metal on the outside of the heads that the t-stats are in? Should I try what I have done so far to see if it works or should I take the covers off and clean that too befor I run the anti-salt stuff through the sytem and take for a test drive. Hopefully I wont bust too many bolts <br />Thanks,