1990 mercury black max 135 2 stroke overheating

[racingdave]

Engine overheats quick under load and runs hot at low speed too,going to the shop today to replace both stats and poppet blow out water passages.My question is can an exhaust divider plate cause the issue?How about the exhaust plate under the power head can that cause it too?I figure go for the most common first before pulling the heads pulling the divider plate and last pulling the power head to inspect exhaust plate and pick up tube.Just put a new pump in yesterday no help.No i dont have a pressure gauge hooked up and yes pee stream is strong but seems hotter then should be to me.Engine runs great fires right up good idle plenty of balls pull off dock lay into it and watch temp climb untill alarm sounds shut off wait 2 minutes fire it back up and idle around back to ramp i can idle it back all day but temp still at 200 give some juice and boom all over 220 and alarm like clock work. Hopping i find something with poppet what do ya think?

 

[racerone]

A blown head gasket can cause overheating.

 

[racingdave]

I need some advise because i simply am not a marine tech but i can swing a mean wrench i dont think its a head gasket,i am replacing my stats and poppet today,What is the hose going to the poppet do?It comes off the top of the power head to the poppet housing i found a yellow insert inside it as i was blowing through every hose i touched and could not blow through that hose so i removed the piece inside it and then i blew through it tons of chit come out of it and i found shell material on my shirt were it hit me could this be my issue?For sure a plugged hose just cant be good i dont know if it could cause such drastic overhearting condition that hose was plugged solid.I am still going to change the poppet iam on top of it now anyway i dont think i will find a problem with it i replaced it last year and the stats opend up in hot water still getting new ones.

 

[Canufixit2]

I need some advise because i simply am not a marine tech but i can swing a mean wrench i dont think its a head gasket,i am replacing my stats and poppet today,What is the hose going to the poppet do?It comes off the top of the power head to the poppet housing i found a yellow insert inside it as i was blowing through every hose i touched and could not blow through that hose so i removed the piece inside it and then i blew through it tons of chit come out of it and i found shell material on my shirt were it hit me could this be my issue?For sure a plugged hose just cant be good i dont know if it could cause such drastic overhearting condition that hose was plugged solid.I am still going to change the poppet iam on top of it now anyway i dont think i will find a problem with it i replaced it last year and the stats opend up in hot water still getting new ones.

A HEad Gasket MAY not be the issue here .... but it's quick to find out with a compression test ...

 

[Chris1956]

You should also replace the water pump impeller, wearplate and 2 gaskets.

In addition, if the gearcase oil looks milky, replace the waterpump base, as ti will have a new driveshaft seal.

 

[racingdave]

Will the hose to the poppet coming from the center of the power head if plugged cause an overheating issue?

 

[Chris1956]

Poppit valve design has changed over the years. My '93 135V6 doesn't have a hose off the poppit, just a weep hole.

You will need an answer from someone with intimate knowledge of your year motor.

 

[Dukedog]

you need ta start with a "complete water pump kit"...

Will the hose to the poppet coming from the center of the power head if plugged cause an overheating issue?

no, but..
if you found debris in a hose then you can bet ya bootie its also gonna be in tha "adapter plates" which will need ta be exposed ta clean out .... jmo

 

[racingdave]

Water pump kit was done yesterday its not the pump its new 2 times over once yearly just did it 3 months ago boat ran awsome 145 all day i got up in some sand 4th of july weekend and ever since been running hot.I thought i damaged the water pump that day so i replaced it again still runs hot, today i changed both stats and the poppet i didnt see anything wrong with any of it and yes a put them in hot water to check them and they open i still replaced them anyway.The only thing that was suspect was the hose coming off the poppet to the center of the power head was plugged up with sand and shell solid,i ran it on the muffs i didnt like what i see i suspect it will contiue to overheat not sure true test is in the water.Duke iam going to have to agree with you i think your right,Do i need to remove the power head to clean out the debri?Should i pull off the divider plate that sits between the two heads a clean out the passages too?

 

[racingdave]

Dukedog what adaptor plate do you mean?

 

[Dukedog]

exhaust "adapter" plates/plate (2 pieces on production motors and one piece on hi performance 2.0/2.4/2.5's) are between powerhead and down housing.. yes, gotta pull powerhead ta get to 'em.. exhaust "divider" plate is between heads.........

sand/shells (dependin' on its make-up) can be tha worst at causin' a clog in places ya can never get flushed out without takin' things apart.... jmo

 

[Chris1956]

Duke, is there any way to blow the adaptor plate out backwards? Say, pull the gearcase and stick a hose in the 'stat holes and give it some water pressure?

 

[Faztbullet]

As Duke sayz...it gotta come apart and manually clean.

 

[racingdave]

Okay i am pretty certan that i did not install the rubber tube seal inside of the water pump housing ,manual says install tube seal inside pump cover with plastic part facing down went through my parts boxes and found it ,hoping iam sucking air or perhaps cavitating the water prior to the water entering the tube WILL THAT CAUSE MY OVERHEATING? sure is a place to start

 

[racingdave]

I think iam good much better on muffs in florida heat out of a hose 150 degrees ,try it out this weekend thank all of you for your input and help much respect. All my fault for not paying attention hope iam good to go cause i sure dont want to pull a power head off a 30 year old boat.

 

[Dukedog]

your not tha first and surely won't be tha last ta miss that grommet... jus good that ya found it before ya started yankin' everything apart!............................:thumb:

 

[Dukedog]

Duke, is there any way to blow the adaptor plate out backwards? Say, pull the gearcase and stick a hose in the 'stat holes and give it some water pressure?

sometimes it works and sometimes it doesn't.. more times it doesn't................ it jus moves tha junk around a bit.

 

[racingdave]

Put it in the water and was exceptable not intirely happy but better then it was .ran hotter at idle speeds then cruise speeds but iam picky 180 idle speeds 150 cruising speeds at least no temp alarm and i can use the boat.i would like a steady temp 145 all the time but it is what it is.

 

[Chris1956]

Idle speed cooling is controlled by the thermostats. Are yours good?

 

[racingdave]

Brand new....along with poppet ..and pump,..maybe i should tyry a different brand i have read there may be a small hole in the t stat should face up to help bleed air out of cooling system i didnt take notice when installing mine and not sure if it even matters.probably should install a pressure gauge looks easy enough on this motor.