Overheating today :(

[irideflatland]

Re: Overheating today

Juniinc, did you just take off the arrester and clean it, or buy a new one?

 

[Don S]

Re: Overheating today

Juniinc, did you just take off the arrester and clean it, or buy a new one?

Usually they can be cleaned. Depends on why they are clogged (IF they are)

 

[Juniinc]

Re: Overheating today

Just clean it,,,
carb cleaner sprayed on, let it soak, blown compressed air, warm water rinse, air dry,,,good to go.
Be very careful of information given by Me,,,

 

[CheapboatKev]

Re: Overheating today

Took out the thermostat and it doesn't overheat
Weird because the shop just replaced the thermostat a couple weeks ago.

I drove it for probably 45 minutes at 4000 RPMs, and it did get very close to the red temp zone but it stayed in the green. So I'm thinking I should just leave the thermostat out...

You realize that the temp gauge is more ballpark than exact temp reading right?
CLOSE to the red, still would trouble me...Whatever you do, you need a tstat in there..

 

[irideflatland]

Re: Overheating today

You realize that the temp gauge is more ballpark than exact temp reading right?
CLOSE to the red, still would trouble me...Whatever you do, you need a tstat in there..

Right, I'm working on getting that figured out, but for the time being it doesn't overheat with the thermostat left out so I think I should leave it that way. Just until I figure out why it's running hot.

Also when wakeboarding we never run it for 45 minutes without slowing down. We are always starting and stopping because people fall. So I'm sure it will run even cooler then.

 

[Juniinc]

Re: Overheating today

burning rich spark plugs probably has nothing to do with your overheating issue.
Be very careful of information given by Me,,,

 

[bruceb58]

Re: Overheating today

burning rich spark plugs probably has nothing to do with your overheating issue.
Be very careful of information given by Me,,,

Just because spark plugs are black does not mean its running rich at cruise. Usually most boat engines run a tad rich at idle so the condition of the plugs is almost meaningless unless they are pulled immediately after a high speed run.

The problem with the OP's spark plugs is that they reach too far into the cylinder and can get red hot and pre ignite the fuel mixture at higher RPMs. That is what could contribute to his problems.

 

[Juniinc]

Re: Overheating today

Just because spark plugs are black does not mean its running rich at cruise. Usually most boat engines run a tad rich at idle so the condition of the plugs is almost meaningless unless they are pulled immediately after a high speed run.

The problem with the OP's spark plugs is that they reach too far into the cylinder and can get red hot and pre ignite the fuel mixture at higher RPMs. .That is what could contribute to his problems

U don't know if its only running a tad rich at idle or very rich at cruise,,,Do U?
"That is what could contribute to his problems"
Let's just say his OP's plugs are getting red hot, contributing to his problem.
So, He probably had those plugs in there for more than he has known.
One day got stuck in sand bay, now suddenly spark plugs acting up & causing/contributing his overheating issue,,,,
Is that your theory???

 

[bruceb58]

Re: Overheating today

U don't know if its only running a tad rich at idle or very rich at cruise,,,Do U?
"That is what could contribute to his problems"
Let's just say his OP's plugs are getting red hot, contributing to his problem.
So, He probably had those plugs in there for more than he has known.
One day got stuck in sand bay, now suddenly spark plugs acting up & causing/contributing his overheating issue,,,,
Is that your theory???

Sorry...lost you after "U".

The long reach plugs could be causing some of his problems(the miss at 4000 RPM for one). The fact that they looked black means nothing.

 

[Juniinc]

Re: Overheating today

In my case it did.
Still haven't answered my question yet,,,
Uhm can't even back it up,,,
I totally understand

 

[irideflatland]

Re: Overheating today

Just went to O'reilly auto parts... bought carb cleaner so I sprayed the flame arrestor. I'm letting it sit for a little and then I'll rinse it with water.

They didn't have the BR6ES, but they had a 'generic' version of the BR6FS so I picked those up. They are short, not like the ones I have now. I'll put those in tomorrow.

 

[Juniinc]

Re: Overheating today

were they dirty/clogged or what? man
When I went to shuck's they did have some NGK,,,they were too $$ ended up picking up some AC Delco.

 

[Don S]

Re: Overheating today

Get the right spark plug number. The E letter is a 19mm thread length, the F is a 10.9 thread length.
Those letters and numbers actually mean something.

 

[irideflatland]

Re: Overheating today

Juniinc are you talking about the arrestor? It looked fine to me, but I sprayed and rinsed it anyways.

Get the right spark plug number. The E letter is a 19mm thread length, the F is a 10.9 thread length.
Those letters and numbers actually mean something.

Damnit, I'll have to return those tomorrow. I would have checked at the boat shop but they closed at 5:00.

The guy at O'Reilly looked up the plugs in his book, and almost all the Mercruiser engines had the FS and not ES so he said I should be fine with those.

 

[bruceb58]

Re: Overheating today

In my case it did.
Still haven't answered my question yet,,,
Uhm can't even back it up,,,
I totally understand

Maybe if you could write in a logical manner I could answer your question.

Seems like I am not the only one here that is having the same problem.

 

[Juniinc]

Re: Overheating today

At least you've admitted that U couldn't answer ,,,
Good excuse though

 

[cedarjunki]

Re: Overheating today

being that its a 1972, 120..............you need to use the serial number to find the correct spark plugs.. assuming its the correct head for the year and hasnt been changed with a newer one or even a 140 head. just going by the year and the engine you have 4 plug choices.
ac-cr44n
ac-cr43n
ac-c44n
ac-r43t



running without a thermostat is not recomended...

you keep insisting on running the engine using it for pulling skiers and joy riding when there are known problems??? and you dont seem to worried about running a third season on the engine oil???

if you really thought you changed a quart of oil when you separated the lower unit....personally i think you had better download the manual from the adult section and start reading before you do anything. also considering that, you say you changed the impeller right? did you do it correctly?? just curious since you thought the engine oil came out of the outdrive.

my advise would be either find a mechanic capable of doing the repairs,
or put the playtime on hold till its fixed and before you blow it up!

 

[irideflatland]

Re: Overheating today

NGK - BR6ES is what Merc recommends for the spark plug.

So I just picked these up from the shop, and they are exactly the same length as the ones that were on there before... the ones you said were too long.
I put them in anyways and I'm taking the boat out today so we'll see how it goes.

 

[irideflatland]

Re: Overheating today

Boat ran terrible today with the new plugs. Still random backfires at top speed, idle was super rough and died once. We always turn it off instead of idle when people get in and out of the boat, and it was tough to start back up every time today.

So I might try the shorter plugs from O'Reilly since I haven't returned them yet.

Oh and right before we got to the dock the boat overheated again :/ WITHOUT the thermostat in.

 

[Don S]

Re: Overheating today

I just posted (or thought I did) a reply that should have been #39 ?????

Anyway, check the spark plug seats in the head, if they are tapered, you should be running the MR43T spark plug.
But, as cedarjunki mentioned. A different head on that old a boat isn't unheard of. But you do need the shorter plugs. If those long threads get carboned up, they could seize in the head when you try to remove them and destroy the threads.