Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

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Larson70

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I took apart the mainfolds on my 1982 Merc 70 hp and there is no thermostat in place. Before I go ahead and put it back together with 35$ worth of new gaskets, I want to be positive there is not supposed to be a thermostat in place. I have talked to a few people on here and have heard that mid 70s to mid 80s Mercury 70's had no t-stat or poppit valves. Someone just reassure me based on their motors please. Thanks, Mike.
 
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Maxz695

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

acording to this page and my motor it does ahve a thermostat http://www.marineengine.com/parts/m...-thru-5579016-usa/exhaust-and-manifold-covers Mine is a 1979 70 hp this is the diagram for it but my engine didn,t have one either nor do I wish to put one there as I,m in FLORIDA 66850
THERMOSTAT (1 required per assembly)
UNITED STATES 4825248 AND BELOW AUSTRALIA 8049849 AND BELOW BELGIUM 9176875 AND BELOW CANADA 7110247 AND BELOW Check your year and serial number at that site
 
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Larson70

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

OK, I am in the upstate of SC and probably don't need one either. Did you put the gaskets in that space as required for the t-stat or just the 3 gaskets (cover to baffle, baffle to block, and the L shaped mini gasket)?
 
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Maxz695

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

just the three gaskets but i,m still in rebuild mode. The only reason you would need one is if you go out on cold mornings or days to get the engine up to temp. These engines I,m fairly new with run fairly hot when warm. I see no need for it and don,t believe it is gonna help with a quick start as I also noticed thes engines take alot of gas and choke to get em going. Heres a litlle tidbit for you. I just put a 1982 70 HP in my 1979 70 HP and the only thing different id the stroke position of the #2 and #3 cylinders. Whether or not mercuy went through the trouble of redisigning a new switchbox for the timing switch is beyond me. They either did or just did like I did and switch the wires on the swichbox for that firing orer from 123 to 132. Tru I coulda just switched the plug wires but that would confuse anyone i ever if ever sold the engine to. Anotherwords if you cant find a switchbox if it ever goes bad. Buy an earlier model switch box and change thred green red and green white wires around
 
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Larson70

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

I just replaced the switch-box and that was the reason I was not getting good spark. In regards to the coils from top to bottom it goes 3, 2, 1. 3 and 2 cross going from the coil packs to the board but the bottom connection on the board goes directly to the coil 1. This has cured my lack of spark problem. Now I'm back to stalling after a bit of running on the water, but when we were testing there was a bit of condensation on one of the plugs which seems to imply that this gaskets I'm replacing were shot (the cover to baffle gasket looked like it was in pretty bad shape).
 
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Maxz695

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

A little unclear but you said your carb was leaking in the bottom when pumping the bulb has that issue been addressed. It may take some time for the crap to get out of the engine but not too long. If your still having issues after fixing the carb. I would think about the sealer you used on the exhaust port and the retourqe of the bolts after running a bit. Heat will have an effect o9n the gasket and retourque is recommended. The only other concern I have is that you could be having water intrusion through the lower end cap seals. Hers my latest post so you can see the outcome of my changeing it This is at present tonight the way it is sitting at the moment. http://forums.iboats.com/showthread.php?t=580632
 
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Larson70

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

i was just trying to agree with the switch board problem and the switch to 132 which i thought you were talking about but what is the recommended torque on the exhaust manifold bolts. There is the outside ones and the 2 inside bolts. It seems like 70 pounds seems to be a universal for manifolds.
 
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Larson70

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

Thanks man. I appreciate it and sorry about your girlfriends brother. Feel free to message me if you think i can help or want to compare issues with your motor.
 
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Maxz695

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

I will be posting more pics of the rebuild and my first venture out but it gona cost for the boat ramp due OCT 1st $30 more dollars and registration is due Nov 11th trailer and boat and Van. I,ll look for you tommorrow i have to back buner some things But I,ll still be around
 
ajgraz

ajgraz

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

Seconded no T-stat on your motor.

The early 70's 650's (65hp 3 cyl) were essentially the same block, but without even a place for the T-stat or poppet. About 1972/73 to 1975/76 in the 65/70hp's they modified the castings and added the T-stat and poppet. After about 1976 in the 70/60hp 3-cyl's they deleted the T-stat and poppet, but kept the same block and cover castings with the spaces for them. (My guess is powerheads were overheating; I would not add one)

If water is on the plug inside the cylinder, sounds like water is probably getting into your cylinder. Apart from a crack in the block (or a cylinder completely corroded through), two places I can think of that can happen:
1) Exhaust cover/baffle gaskets or corroded-through baffle plate (sounds like you're addressing this)
2) Exhaust plate gasket bad, letting water into the chamber at the bottom of the crank, then leaking in through the lower crank oil seals (unfortunately, gotta pull the powerhead to address this one)

If water is on the plug outside the cylinder, you probably got a leaky rear cylinder cover / gasket.
 
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Maxz695

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

Inbox cleared ajgraz you got mail thanks
 
Faztbullet

Faztbullet

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Re: Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?

Is anyone 100% positive that a 1982 Mercury 70 hp does not require a thermostat?
Click to expand...
The 1982 model does not get a t-stat, only the early ones as previously posted....
 
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