1986 DT115 cooling problems

[fngboy]

I have a 1986 blue fin with a 1986 suzuki DT115 on it. I just got the boat non running, I took it to a suzuki dealer who cleaned the carbs and got it running said it has water coming out of the tattle tale hole, told me the light comes on for a little while but goes out. I took it to the lake and just like he said but the light comes back on again and goes off and when going fast motor makes white steam even though water is coming out of the tattle tale hole. Anyway replaced water pump and the seal around the tube that separates the exhaust. Both look great, no cracks in the waterpump and the seal was just as tight as the new one. Also purchase the seal on the tube that goes into the waterpump bottom one and top one part numbers 1,3,5. Bottom one part number 5 looks bad hasn't shown up yet but will replace it. I put the garden hose on the tube and no leaks up on the motor, thank God, but a pencil sized stream of water comes out of the exhaust area. I figured it was the top seal. On the diagram part number 1. mine don't look bad it feels rubbery to the touch and it feels tight on the tube I got a new one coming. question how do you replace it? its bigger than the hole that part number 3 goes into? I also bought a new temp sensor but the stream has me worried and I would think if you put water up the tube and the thermostate is closed it can't go anywhere. Can anyone help? parts should be here tomorrow. It might just be part number 5 causing all the problems. Maybe a little RTV on the tube when I put it back into seal #1? thanks JOHN

 

[fngboy]

Well I got the new parts and am going to put it back together today and take it out on the lake. thanks JH

 

[fngboy]

So the thermostat was bad so I replaced that. I ran the motor and it works great at idle. The water comes out hard out of the tattle tale hole and it runs pretty good. anything off idle the light and alarm comes on and the water from the hole goes down until it is no more. This happens when in neutral also. I am thinking one of the cylinders in blowing some exhaust into the water jacket, maybe a head gasket or a cracked head or block. Big bummer. I can still fish I just have a 115 hp trolling motor that trolls at 2.8 MPH. Anyway have to fix the transom and the floor both are bad. Called the previous owner who got it from another guy and we are going to figure something out. probably looking at a newer motor but we will see. thanks JH

 

[99yam40]

leak down test will tell you a lot

 

[fngboy]

Back at it in 2016. Heads were warped bad got themmachined flat. New gaskets again. Top of the motor perfectly flat. Still same problem. friend said exhaust plate/cover gasket. Looks like there is a gasket on both sides of the exhaust cover. I don't understand what the exhaust plate does?

 

[James R]

Exhaust gasses pass on one side of the plate and cooling water passes on the other side to cool the gasses before they exit the prop. If there is a leak problem in this area water can enter the cylinders via the exhaust ports or gasses enter the water system. This can be catastrophic to the motor. Usually this is evidenced by very clean plugs

 

[fngboy]

So the previous owner had it at a mechanic who was trying to track down the problem so most of the parts I am changing have been changed. Someone has taken that plate off but didn't replace the gaskets. like I said I pulled the heads and got them decked and the pistons cylinders etc look great it runs great.

I replaced all the parts in the lower unit that are anywhere close to the water pump and the lower unit has a new prop shaft and seals and all that stuff also.

On another post here someone with a DT140 put JBweld somewhere in the lower unit because there was corrosion there and it fixed his problem. I didn't see anything but maybe that's my problem. Another guy said he has 2 lower units one over heats and one doesn't. When I connect the hose to the earmuffs it doesn't over heat so water pressure from the bottom fixes the problem. I went to the lake left the boat on the trailer ran it up and anything off idle, the tell tale starts to stop and the idiot light and alarm go off.

we are having fun now. but I do feel like I am narrowing it down a bit. thanks

 

[fngboy]

found the problem The tube that brings water in from above the propeller goes through the exhaust area and into the water pump there is a grommet/gasket that I replaced last year. Well when I pushed the tube in it didn't go into the hole all the way it pushed the grommet into the water pump so exhaust went right in there at high idle. found that today fixed it just got back from the lake. thanks jh

 

[tommarvin]

Your a lucky guy, just to be safe I would still do a leak down test like 99yam40, HF has them for 40 bucks,you-tube has great videos on how to do them.