1991 Evinrude 88 spl overheating deflector replacement

Clyde Jones

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Hi there I'm new to this forum and new to being a boat owner. i do have mechanical experience being that i am a mechanic who specializes in toyota and lexus (so let me know if you have a question about cars :joyous:)

so i have this 88 spl that over heats pretty quickly and at idle.. the right bank gets up to 202 and the left bank gets up to like 188.. thats when i decide to shut it down.. water seems to be coming out of all the ports normally and the water coming out of the pee hole is warm. starts up and runs great just seems to be getting hot.. im running it at 50:1 mixture now.

I have already replaced the water pump and installed thermostats but she is still getting warm. so my next guess would be to replace these 'deflector tubes' I've recently been reading about.. my question to you folks is how do i replace these tubes? are they fitted over something or do they just sit in a cavity? and from what i've gathered they are approximately 3/8" in diameter but how long are they?

my other question is when removing the cylinder head covers is there anything special or is it pretty straight forward? there is a rod coming out of the left bank on the top (#2 cylinder i believe) next to the spark plug.. what is that? do i just remove that nut and slide it off or do i have to mark it or something..

any help would be greatly appreciated.
thanks,
Clyde
 

boobie

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The water deflectors you're talking about are under the cylinder heads. What happens is they usually swell up and block off the water flow in the block causing an over heat.
 

Clyde Jones

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How long are those hoses? and from what i read on joe reeves post i can just get those hoses at an automotive store...?
 

emdsapmgr

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water diverters.jpg The left hand deflector in the picture is considered "normal". The right one is an example of one misplaced.
 

ondarvr

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Don't worry about the length, just measure what you take out and replace them with a similar hose. You can match it up at an auto parts store, or buy the actual part from a dealer.
 

Clyde Jones

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Awesome thanks for that pic emdsapmgr!

and wow i didn't even think of purchasing the hose on the Evinrude website.. gah i just ordered 4. thank you ondarvr
 

Bosunsmate

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If that doesnt fix it. Drop the lower unit and hook a hose up to the inlet pipe. They normally slip on pretty easy.
That way you can isolate the problem to either the powerhead or the LU
 

Clyde Jones

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got the heads off today! broke a few bolts on the cylinder head cover but luckily none of the head bolts broke... so im pretty sure those deflector tubes were swelled shut and there was no movement of water through. New tubes are shipping at the moment...

anything special about the installation of those tubes?
 

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racerone

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Water does NOT go through these tubes.-These tubes guide water around the cylinder block.-Solid rubber material will work too.
 

Clyde Jones

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oh. so the only way those tubes fail is if they get misaligned or break? do you think excessive corrosion next to those tubes can cause overheating?
 

emdsapmgr

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The deflector rubber tubes do guide the water in a specific path around the cylinders. Comparing your block pictures with the block in response #4, above, you've got more than just deflector problems. The whole cooling system around all 4 cylinders needs a complete cleaning. Is this a saltwater engine? As bad as that cooling system looks, the pistons and cyl walls do not look distressed-despite the water restrictions around each cylinder.
 

Clyde Jones

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Yes there is a lot of corrosion/build up in there. i took a pick and pipe cleaner and spent some time cleaning it up best i could. so i believe the heads, covers and block will flow much better now.

I'm not sure the past of this motor, whether it's been in salt or fresh water.. I do know the boat has been setting for several years though so im thinking time has something to do with the build up as well....?

..and yes it does seem there is no unusual wear in the piston and sleeve itself. there is a little bit of pitting at the exhaust port i believe but there is nothing too dramatic with the mechanical section
 
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oldboat1

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So Clyde, what was the compression? It would be good to have a benchmark to check after new head gaskets and resurfaced heads. On the cooling, think your model has a cover on top of the head -- opens up water passages(?). I think you also have the bubble back exhaust. I would be inclined to pull off covers and clean under everything, also t.stat housings, etc. -- then flush. I don't know if you run in salt water, or maybe inherited a salty(?). And maybe not salt corrosion in yours (although the broken bolts kind of give it away).
 

racerone

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The original blocks on the 88 hp models did not use the " bubble back " exhaust covers.
 

oldboat1

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looks like the rear cover comes off to access t.stats -- don't know how difficult it is to get at them. But apparently a water passage cover on top of the head, and that's got to be useful for cleaning.

good to douse everything with Powerblaster or some kind of penetrating oil to try to avoid more breakage. You've probably been doing that.
 

Clyde Jones

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thanks oldboat, i have not done a compression check on it but when i ran it it seemed to be firing well, once i get everything back together i will run a compression check.

do the heads and block need to be resurfaced by a machinist or can i just take a scotch pad on an angle grinder to clean the surface?

as far as the thermostat housing goes, i pulled it off a while ago and cleaned inside it, installed a tstat kit so i hope that's all good to go.

i have been treating the threads well, i have access to my auto shop so i have tools and anti-seizes.. i managed to get all the broken bolts out and chased all the threads in the head/block and chased all the bolts.. minus the new ones i have to purchase.

there is that large plate that sits between both cylinder banks (more coolant passages i'm guessing?) but i'm afraid to take that off unless i have to, seeing what happened to the head i don't want to be playing doctor on all those bolts.

really appreciate the responses guys!
Clyde
 

oldboat1

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Sounds like you have it handled (know what you mean about hesitancy re. bolts). On the head -- a little more gentle than you are planning, I think. Use a smooth surface (some guys like a piece of glass), and a piece of wet/dry -- 400 or 600 grit is good. Use a figure eight motion and look for an even shine on all the surfaces.
 

Clyde Jones

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so i installed those tubes and got the heads on today. those tubes were tough to get in, i'm guessing because of all the corrosion i had..

ran out of daylight and got hungry so i wasn't able to finish
 

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emdsapmgr

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Looks like you've done a lot of cleaning on the block cooling system! Nice job. Don't forget to re-torque the heads after you run the engine through a few heat/cool cycles.
 
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