Help! 1968 Mercury SS 1000 hp overheating

[Dale Speck]

Hey guys, I need help! Just got my "new" Merc Started and running good just to find out it's overheating. Seems to be pumping plenty of water, but the water isn't as hot as it should be. Could it be the thermostat? If it is, where do I locate it?

 

[emckelvy]

Re: Help! 1968 Mercury SS 1000 hp overheating

, but the water isn't as hot as it should be./QUOTE]

OK, I'm cornfused, not as hot as it should be means the motor's overheating?

Is the block getting too hot to touch? If so, that's overheating and you should check your impeller.

If the exhaust manifold cover gets no more than lukewarm and the block stays fairly cool while you're running the motor in a barrel or flusher, you've got enough water circulating thru the motor.

If you're running on a flusher, be sure you have enough water pressure to cause a bit of water to spill by the 'muffs' after you start the motor.

You can also tell if you've got water circulation by the telltale, also water flowing down the exhaust and out the prop will be noticeably warmer than the water going in.

Hopefully that covers your question. Inline Sixes don't have thermostats, so the water flow thru them is fairly uncomplicated.

If the above don't do the trick for ya, post with more details and we'll attempt to get to the bottom of it. HTH...........ed

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Sorry about the cornfusion, THE WATER coming out is only luke warm, the block gets very hot, very quick.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Sorry about the cornfusion, THE WATER coming out is only luke warm, the block gets very hot, very quick. Don't know anything about Mercs, I got this boat unbelievably cheap with the Merc on it and a '66 Johnson Meteor 100 hp with it ,free. Really thinking about putting the Johnson on it but I keep hearing nothing but horror stories about the Electromatics. Any advice on this matter greatly appreciated.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Sorry about the cornfusion, THE WATER coming out is only luke warm, the block gets very hot, very quick.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Sorry about the cornfusion, THE WATER coming out is only luke warm, the block gets very hot, very quick.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

sorry all, not sure why it reposted so many times, it won't let me delete them either...

 

[OldMercsRule]

Re: Help! 1968 Mercury SS 1000 hp overheating

So ya like CORN eh? LOL LOL LOL Me too!

Me thinks Ed will have ta tell ya how to take off the inspection plate/ water jacket cover ta see if the passages are full of sand or somethin'. Hope the engine is a fresh water girl or you will be breakin' bolts n' drillin' 'em out when ya put her back together.

I bet some weeds or sand has blocked somethin'. Make sure the tell tale is hooked up to the block at least at #3 n' not directly to the inlet at the base of the block.

Is the block hot at the top of the tower n' jus' warm at the base? Try to get a specific as possibe so Ed can help ya.

Good luck, BTW the ol' girl is worth fixin' IMHO, as it will blow the doors of the Johnnyrude n' she is a lot purdier tooooooooo!

Me overpriced $.02. JR

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

The whole block is getting hot enough to fry eggs on, what is the tell tale?

 

[Ohioriver]

Re: Help! 1968 Mercury SS 1000 hp overheating

Tell tale is a small stream of water comming from a small rubber hose at the rear lower cowling area on the motor so you can tell water pump output. Should come out as a good stream, not a dribble. Thats one way to tell how good your water pump is working.

 

[OldMercsRule]

Re: Help! 1968 Mercury SS 1000 hp overheating

The whole block is getting hot enough to fry eggs on, what is the tell tale?

When you tell us it "seems to be pumpin' PLENTY of water" we assume ya know what yer talkin' about. What do you base this statement upon......... pray tell????????

Usually that means the "tell tale" as explained by the previous poster is peeing a strong stream. Does yer engine have a strong stream of water squirting out at the rear starboard base of the powerhead or not???

If not: drop the LU and service the water pump.

You may need a manual, no on second thought: YOU DO NEED A MANUAL.

If so: where is the rubber hose for the tell tale hooked to on the block of the engine???

DO NOT HEAT UP THIS ENGINE WHERE YOU CAN FRY EGGS. Fix this problem.

Hope that helps ya sort through this issue.

Good luck, JR

 

[emckelvy]

Re: Help! 1968 Mercury SS 1000 hp overheating

If, after pulling the lower unit you don't find a fried impeller (I bet you will), you can either blow air up the copper water supply tube to check flow thru the motor, or connect a source of water to the tube and see how water flows thru the powerhead.

This should tell you a lot. You should get a virtually unrestricted flow thru the motor, dumping out the bottom of the powerhead, down the exhaust tower and out.

If you find water flow is restricted, next thing to do would be to pull the back cover off the block and check for silt/sand buildup. Water circulates all thru the big passages around the cylinders, if silt builds up it impedes proper circulation.

With the cyl block water jacket cover off, you can run water up the supply tube and watch it flush out the block. That'll tell you a lot in itself.

Just use care with the cover bolts, they are only 1/4" and if this motor is a Salty Dog, they'll likely be badly stuck. Apply heat with propane or MAPP torch and gently loosen. After heating, a judicious application of PB Blaster or other suitable pen oil will help.

Last thought, it's not unheard of for rubber shards of a lunched impeller to find their way up the water tube and cause partial or total blockage. A wire up the tube might find same.

Let us know what you find when you get that lower unit apart.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

O.k. , I don't know my arse from a hole in the ground. I went to youtube and watched a video on how to take the lower unit apart and alas! I discovered the peehole! My motor has water coming out of two holes on the back of the lower unit about mid way up , but not "peeing" at all. I don't remember if I mentioned this or not, but this is my first bonafide Merc, The only other thing I have made by this company is a 1950 Wizard 6hp that runs like a new one.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

I know how you metal heads do so love photos, so here are some of my Wizard.

 

[OldMercsRule]

Re: Help! 1968 Mercury SS 1000 hp overheating

O.k. , I don't know my arse from a hole in the ground. I went to youtube and watched a video on how to take the lower unit apart and alas! I discovered the peehole! My motor has water coming out of two holes on the back of the lower unit about mid way up , but not "peeing" at all. I don't remember if I mentioned this or not, but this is my first bonafide Merc, The only other thing I have made by this company is a 1950 Wizard 6hp that runs like a new one.

Very kool, then the fix is real easy.

Drop the LU, (get that manual first ). The only bolt, (total of six), not obvious n' within sight is under the zinc. Change out the impeller, (and pump case too, if it is a salty dog or in poor shape).

Inspect and change out the LU gear oil (inspect fer water intrusion); if some: change out the seals under the pump base and make sure to put the small o-ring type gaskets on the two plugs in the LU.

That ol' girl has two fuel pumps on the starboard side of the block, if she starves fer fuel once you have fixed the water pump n' run her @ WOT: change 'em.

When ya pump the fuel bulb firm inspect all fuel lines fer leaks. I replumb me old girls with fuel barbs n' modern alcohol resistent fuel lines if they leak, (far toooooooo spendy to get the factory style gas lines), IMHO.

Unscrew the distributor cap n' inspect n' clean inside. The wires screw into the cap so don't pull out! Don't remove the rotor as ya can't without removin' the whole assembly. Check the wirein' harness n' replace if weak, (ya can buy that one right here on iboats): cheap!!!!

There are fuel screens on top of each carb that need gaskits if ya take 'em apart. N' if there is any idle or other problem then ya gotta R & R the carbs n' if ya do that YA MUST LINC n' SYNC!!!!

I don't generally fix things that aren't broken. The water pump bein' one exception. Fuel pumps are also real easy to fix the rest gets progressively more difficult.

Once ya fix this girl you will be surprized how wonderful an engine a 41 year old girl can be. Then you will know why these inline6s were the biggest selling high powered outboard engine on this particular planet from the late 1950s to 1988.

BTW many parts are interchangable from 1962 to 1988 like LUs, power trims, (they did change PT in 1985 or some such), CDI boxes (1967 to 1978 or 79).

So not only are they the purdiest engines ever built, butt they are very powerful fer their light weight, n' very dependable in fresh water. N' most Liberals in major metropolitan areas really hate 'em n' sneer at 'em from their 4-poke powered heavy boats that you will blow away with yer smokin' screamin' purdy ol' Black girl once ya put her to the wall ta show 'em yer stern.

BTW: The Liberals hatred of 'em makes parts engines (or maybe good runnin' spares), real inexpensive to acquire. Once ya go through yers you will know what to look fer when ya pick up another one.

Good luck, JR

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Thank you so much for all of yer help and invaluable information. As I stated earlier in the posts, I got the boat cuz the guy said he put it in the water and it ran terrible.I don't think he got it running at all, the fuel in the cell smells about 5 years old.All i did is change fuel cells to a 6 gal. potable and it started right up and ran like a scalded dog, until I noticed it over heating. Its a freshwater motor. looks almost new except for the red stripes sunbleaching to silver.I'll post pics.Besides, I have 20 dollars invested in the boat, motor, trailer combination so I can afford to spend a little.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

Thank you so much for all of yer help and invaluable information. As I stated earlier in the posts, I got the boat cuz the guy said he put it in the water and it ran terrible.I don't think he got it running at all, the fuel in the cell smells about 5 years old.All i did is change fuel cells to a 6 gal. portable and it started right up and ran like a scalded dog, until I noticed it over heating. Its a freshwater motor. looks almost new except for the red stripes sunbleaching to silver.I'll post pics.Besides, I have 20 dollars invested in the boat, motor, trailer combination so I can afford to spend a little.

 

[Dale Speck]

Re: Help! 1968 Mercury SS 1000 hp overheating

http://s243.photobucket.com/albums/ff238/bad_habits1_photos/Merc 1000 SS/