2016 50hp TLDI Getting hot!

[shallowwatersoul]

Hello I just bought a 50hp TLDI Tohatsu 5 months ago. The motor is set up on a 4 inch setback jack plate. I have the motor about as high as I can go with out loosing water pressure. The problem I am having is at WOT the temp light comes on and shuts me down for about 5 seconds. I have done my own experimenting as far as checking the temperature coming out of the pisser by feeling it with my hand and it is not very hot at all. I am getting good pressure also. I am starting to think that maybe this motor has a sensor somewhere on the tuner or in the mid section? Has anyone been into one of these new TLDIs and can confirm that? I do not have a very good feeling trying to run this motor in the marsh in the winter time with a full duck hunting load and having the motor shut down and knock me off plane leading to me pushing my boat out of a 200 yard flat...And also yes I know the motor probably should be lowered to the water but my 59 cubic inch Merc never had an issue running at this height for multiple years...

 

[Sea Rider]

Welcome to Iboats,

Both are different OB brands, as such could have slight larger or shorter lower legs, no matter if both are S-L-XL OB's.

Having good water pressure is no indication that OB is correctly transom height seated. Tohatsu OB's as Yam ones, loves running with water flow at plane to skim right under upper water deflector plate as in the example :

https://www.youtube.com/watch?v=oBeZjaA76VM

Go for a wot spin with OB trimmed to 90? and deck weight well distributed and check by pulling out head over middle transom at which lower tail height is middle water flow passing by. Seems OB sits way high and water intakes don't collect ideal water amount to cool properly that OB running at wot.

Is it possible to ged rid of the aft jack plate and bolt OB directly on transom ?

Happy Boating

 

[shallowwatersoul]

thank you and yes I am trying the motor mounted directly on the transom as of right now. I can't seem to understand why the pisser would not be a good indication as far as temperature wise to tell if the block is getting hot or not? I'm starting to think that this over temp issue is due to the bottom of the cavitation plate being out of the water. Can you explain to me why they use a water pick up under the cavitation plate? It seems to be loosing water flow out of the three long cut holes down by the lower unit at WOT. I tried experimenting and using duck tape to plug off the intake under the cavitation plate and the over temp alarm never came on, that's the reason I thought that Mabey there is a temp sensor in the midsection...

 

[shallowwatersoul]

Also I have been looking at the lower unit and on the main screen water pick up Tohatsu uses only about 2/3 of the screen. The other 3rd is blocked off. That does not make any sense to me.

 

[pvanv]

Couple things.
First, you need to specify actual model for servicing. I assume you have an MD50B2.
There are two temp sensors; one in the block, and one at the compressor; nothing is in the exhaust housing.
The reason you are overheating is that you are sucking air from under the antiventilation plate. The motor is too high.
The telltale is at the bottom of the block, which is usually cooler than the head. That is why it didn't burn you.
The TLDI is not a "new TLDI"; they are based on decades-old 2-stroke blocks, fitted with DFI fuel systems.
The 3 long holes above the plate are exhaust relief slots for operation in reverse.
The water inlet strainers need to be fastened to the side of the LU, and that is why the entire strainer is not used; it is mounting area.
That motor is available with jet drive, which may have been a better choice for your rig.

 

[shallowwatersoul]

My buddies 1993 m40d uses all of the surface area on the water intake screen, seems to me they would want all the cooling they could get with all the extra stuff added to this motor like the air compressor and stuff like that. Do you happen to know what temperature would set the sensors off? And also is there any NPT port I can screw into with a tubing fitting and thermocouple and read temperature? Yes I have a MD50B2. Is there any disadvantage of blocking the antiventilation plate off?

 

[Sea Rider]

If riding with anticav plate exposed at speed, OB sits way high, assume OB is fully seated down on transom, if so will need to install the jack plate and rise OB as suggested. Don't block anything, OB was meant to run that way...

Happy Boating

 

[pvanv]

My buddies 1993 m40d uses all of the surface area on the water intake screen, seems to me they would want all the cooling they could get with all the extra stuff added to this motor like the air compressor and stuff like that. Do you happen to know what temperature would set the sensors off? And also is there any NPT port I can screw into with a tubing fitting and thermocouple and read temperature? Yes I have a MD50B2. Is there any disadvantage of blocking the antiventilation plate off?

If you want to see what temps the motor was experiencing, read-out the ECU. You need a tach and a Factory service manual to do that. You can use an IR thermometer to see the various temps at different points of the motor. When sucking air, in addition to a possible overheat, you risk water pump damage, and you get low water pressure. Lower the motor a little, and all will be well.