How do i check Mercury thunderbolt 850 cooling system?

[Crazy Professor]

Hello Boaters!
When running this engine with hose attached, warm water only comes out of the vents at the bottom of the leg not the small hole on the rear right of the power head, or the two ports at the lower back part of the power head. Is this a problem? What should i look for? I have never run this engine in the water as yet. I have already inspected the impeller and found it intact, but with some wear on the outer edges of the impeller vanes. I forced water up the cooling system tube inside the leg that connects to the water pump, with the same results.
Thanks for any help in advance.

God Bless

 

[carholme]

Re: How do i check Mercury thunderbolt 850 cooling system?

Run a piece of weed whacker line up the tube at the right rear and see if it is clogged. Mud daubers love to get in there and block the tube.

You say it is a Mercury Thunderbolt but it is a Mariner painted and cowled engine. Do you have the s/n for the engine?

Gerry

 

[Chris1956]

Re: How do i check Mercury thunderbolt 850 cooling system?

The square holes at the base of the powerhead are exhaust relief. With the motor in neutral, and in the water, cooling water may exit there. The telltale stream should have a flow whenever the motor is running. On a flusher device you should see water from the prop, gratings above the anti-ventilation plate and the telltale.

If the impeller is a bit worn, as you have said, it is a good idea to replace it, the wearplate and the two gaskets.

 

[Crazy Professor]

Re: How do i check Mercury thunderbolt 850 cooling system?

Run a piece of weed whacker line up the tube at the right rear and see if it is clogged. Mud daubers love to get in there and block the tube.

You say it is a Mercury Thunderbolt but it is a Mariner painted and cowled engine. Do you have the s/n for the engine?

Gerry

I quoted the engine as a mercury simply because it is easier to find information on the Mercury engine that is identical to the Mariner 85hp, so far as I can tell. I wish I knew the S/N. I can not find it anywhere. There is a number stamped on part of the engine block I thought it may be, but no number or compliance plate as I have teen told is usually found on mercury engines.

Thanks for the tip. I will try it out.

 

[carholme]

Re: How do i check Mercury thunderbolt 850 cooling system?

Well, as a Mariner 85, it is a very limited production in 1977.

85 4731898 - 1977 Which means s/n 4731898 thru the end of the production run

From here:

Mariner 60-350 hp, produktions?rslista, modellguide

Parts Listing:

Mercury Parts, MERC 850

Some info for you from the condensed version of the service manual. Download it soonest as the link is shortlived.

Small Engine Repair Reference Center Home

Gerry

 

[Crazy Professor]

Re: How do i check Mercury thunderbolt 850 cooling system?

Well, as a Mariner 85, it is a very limited production in 1977.

85 4731898 - 1977 Which means s/n 4731898 thru the end of the production run

From here:

Mariner 60-350 hp, produktions?rslista, modellguide

Parts Listing:

Mercury Parts, MERC 850

Some info for you from the condensed version of the service manual. Download it soonest as the link is shortlived.

Small Engine Repair Reference Center Home

Gerry

Hello again,

I really appreciate all the help you and others have been able to give me!
I was not able to download the link as i was busy all weekend and not on the computer.

Is it possible you may be able to refresh it for me?

Thanks again....

 

[carholme]

Re: How do i check Mercury thunderbolt 850 cooling system?

Small Engine Repair Reference Center Home