1990 Evinrude25 blew head gasket, now what?

Cofe

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Just bought untouched evinrude 25 1990. It blew the head gasket, melted the water pump, water supply gromet burnt, bad thermostat. Is there anything else I should look into on this motor? The pistons and cylinders are fine. I am waiting on power gasket set, and lower unit seal kit. I am planning on running this motor without a thermostat. Would this cause Problems? "The thermostat is at a 145 degree setting. :confused:
 

rusirius

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Re: 1990 Evinrude25 blew head gasket, now what?

If it got that hot I'd check the water deflectors if it has them... Also make sure to check / plane the head.. .Good chance it may have warped...

Any reason you don't want to replace the thermostat? I mean considering how cheap it is, even compared to the cost of the gaskets and things you've ordered, why not replace it?

As for causing problems, it'll make the motor take longer to warm up and potentially not stay up to operating temperature at idle or slower speeds... Those could lead to more / quicker carbon build up, fouling, etc...
 

tashasdaddy

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Re: 1990 Evinrude25 blew head gasket, now what?

put the tstat in it. it is there for a purpose, or the bean counters would have never let them spend the $$ to put one in. the motor has to run at the proper temperture.
 

5150abf

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Re: 1990 Evinrude25 blew head gasket, now what?

Had a buddy that actually melted the red plastic pressure releif into 3 peices and we put a new head gasket on it and he was fine, compression was 145 cold so you might luck out.

Use a peice of glass and some sandpaper to true the head before you reinstall and put the Tstat back in, as TD said it wouldn't be there if it wasn't needed, if you don't the engine will always run cold.
 

kenmyfam

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Re: 1990 Evinrude25 blew head gasket, now what?

Use the thermostat !!!! it has a purpose.
 

Cofe

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Re: 1990 Evinrude25 blew head gasket, now what?

Thanks for the input!
Where are the water deflectors? Are you talking about water passages in the cylinder head? Or Where?? I have decided to put in a new thermostat, but from what I can deduce, the faulty thermostat caused this melt down. It could have been that a piece of the water pump impeller, or debris that got lodged in the stat.
I was also wondering if there is a way for water to get into the intake portion of this small motor. Gasket? I need to get a good manual, all I have is a pdf. version of several different years, and sizes of Johnson/Evinrude motors. It gets tricky on what is the proper thing to be reading pertaining to this motor. Any suggestions on what manual I should get? Thanks All!
 

Mas

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Re: 1990 Evinrude25 blew head gasket, now what?

I have decided to put in a new thermostat, but from what I can deduce, the faulty thermostat caused this melt down.

More than likely, the problem began with water pump failure..either due to dry starting or failure to replace during scheduled maintenance.

Pretty hard to "melt" something that is underwater!

MAS
 

Cofe

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Re: 1990 Evinrude25 blew head gasket, now what?

More than likely, the problem began with water pump failure..either due to dry starting or failure to replace during scheduled maintenance.

Pretty hard to "melt" something that is underwater!

MAS

Hi Mas, I had just put in a new impeller before this melt down. Everything worked fine until the overheat happened. I was wondering if the head gasket had a leak between the water and exhaust side, and the compressed hot exhaust went down the water tube to the water pump, thus melting it under water. The motor was at full speed in the water when this happened.
 

5150abf

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Re: 1990 Evinrude25 blew head gasket, now what?

Get into the iboats store and order an OMC manual,not Clymers,Seloc and you know about the cds.

An OMC manual is specific to your engine, if it is in the manual it is your engine and your engine is the only thing in the manual, worth every penny.
 

Mas

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Re: 1990 Evinrude25 blew head gasket, now what?

Hi Mas, I had just put in a new impeller before this melt down. Everything worked fine until the overheat happened. I was wondering if the head gasket had a leak between the water and exhaust side, and the compressed hot exhaust went down the water tube to the water pump, thus melting it under water. The motor was at full speed in the water when this happened.

Maybe a clogged intake with weeds/plastic debris??

MAS
 

Cofe

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Re: 1990 Evinrude25 blew head gasket, now what?

Here are a few things I found out about my 1990 Rude 25 that may help someone.
First I did a compression check on the engine. I had the type of guage that builds up pressure as the pistons go back and forth several times, and it gives me the total built up pressure. The problem with this is that in a 2 cylinder engine with a bad head gasket between the two cylinders, will eventually give a steady compression reading between the two cylinders, and will be an erroneous reading. My plugs were fouling because I had to enrich the idle fuel, and water was getting into the cylinders from the bad head gasket. The plugs did not have any rust,(probably due to the rich mixture). I ended up replaceing the head gasket, and thermostat. I stoned the head, and it was dished between the two cylinders. At first I thought it was the carb, and had a kit put in, this did not help. I also put a kit in the fuel pump, and the motor starts right up now. My fuel pump must have been weak. I hope this will help you out, and I am finally happy to get my boat back up on the river.
PS. (Remember to launch your boat and go up stream on a river, so if something happens, you can float back to your trailer.):D
 

Rick.

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Re: 1990 Evinrude25 blew head gasket, now what?

That was good of you to report back. This is a learning site for us all and so many take the information and run. Glad to here your running again. Rick.
 
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