Evinrude 1990 90hp E90TLESB cooling problems & running rough

[MichaelP]

I'm in the last stages of restoring a 1974 Starcraft Chieftain and fired up the motor for the first time last week. I bought the boat package 10/2010 and had the engine winterized and was told it sounded an alarm but ran well and I should clean the carbs. This boat has been soaking in the Atlantic for a while. I wasn't too concerned about that as I planned to go through it durning the winter. With service manual in hand I spent some time on it that winter replacing fuel lines, thermostats and rebuilding the carbs. Last week, after running fine for about 5 minutes I got a constant alarm (over heat) and it stared to run rough so I shut it right down, the whole engine felt hot to the touch. Pulled the cylinder covers and found the port side packed with salt.

I proceeded to pull the heads and exhaust manifolds cleaning everything and blowing out all the ports with air. Put it all back together with new gaskets and diverters. One of the diverters on the lower port side was installed on the wrong side of the bolt hole and was covering one of the 2 water slots on the head gasket but now its in the correct spot per the book and the grooves in the block. Over heated again and running rough. Starboard cylinder bank was hot I'm wondering if I disloged something deep in the block that I didn't see. Another problem may be that the lower diverter on that side wouldn't seat all the way in by about 1/4" whereas all the others did. The tell tale has good flow and I know that I'm getting flow on the port thermostat hose because it sprayed water from a split at the hose clamp. Replaced hoses and blew air into the hose nipple on the starboard block. Now I can't get it started. It fires for a split second just enough to kick out the starter and that's it. I'm thinking about taking it in to a pro but it might take a long time to have it looked at. I'm confident I can fix anything on this motor myself but with multiple things going on it's tough to trouble shoot. Any help would be appreciated.

 

[MichaelP]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

Update...Like a dope I had the coils on the port side reversed which would account for that side not getting so hot yesturday. Now it runs fine but it still over heated. Just a sprinkling or spray if you will of water is flowing through either thermostat hose (the temporary ones I'm using are reinforced clear 3/4" tubing) but still getting a good stream from the tell tale. Not having the 1 deflector seated all the way and the thermostats are suspect at this moment. I'm going out now to pull the stats I installed 18 months ago to inspect.

 

[Haffiman]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

Pull the lower unit and check impeller and waterpump. Attach a hose directly onto the water tube and 'flush'. As you already have the clear hoses for test, it might be easy to monitor even flow.

 

[MichaelP]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

Thanks for stoping by Halfiman. I may have found the problem. I ran it with the stat housing removed and there was all kinds of flow from both heads and she ran nice and cool. When I installed the stats I used a bit of silycone and some of it was covering the small hole in the center of the stat manifold. Could that be preventing the stats from getting hot water and opening them up? PO claimed to have just had the pump replaced just before I bought her. He is a repectable local gentleman and I take his word. Not ruling out the possibility of the lack of use causing damage with the impeller but it's pumping like a banshee at the heads.

 

[Haffiman]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

If the bleed hole is blocked and you use thermostat without bleed-holes, it will create a vapor lock. Water not reaching the thermostats.

 

[MichaelP]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

That was the problem! I cleaned the t-stat housing and reinstalled then everything worked fine. As you can see in this video the water flows through the head just fine. Whith the t-stats installed I can see a slow but steady strem in the hoses and the motor never got warm enough at the lower rpms for the t-stats to open up. Its all good now. Thanks for the help!!!

 

[jb_wi]

Re: Evinrude 1990 90hp E90TLESB cooling problems & running rough

Michael - I have a similar motor I'm working on and came across your post while searching the forums. I have the 115 VRO and while running on the muffs, the starboard side cylinders are getting quite hot, but the port side seem to stay cool. (All 4 cylinders are firing fine).

When you said you installed clear hoses, are you talking about the 3/4" or so hose from the cylinder to the thermostat housing? I may give it a shot to see what kind of flow I am getting. (I did disconnect both hoses from the cylinder side like you did in the video, and I have great water flow there. The problem with my motor from what I can tell, is that the manifold is a bubbleback style, and I don't think I canget the thermostat housing out without removing the powerhead, unless I'm looking at something wrong.