1968 Evinrude 40 hp Big Twin Overheating

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

It just came unstuck!!! More details to follow!!!

 

[kfa4303]

Re: 1968 Evinrude 40 hp Big Twin Overheating

SWEET!!!!!!!!! Patience is a virtue. Your ingenious puller must've done the trick. Now you got something to work with. I want to know how it could've goten so stuck in the first place :/ ?

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

What a journey. As kfa says, patience is a virtue. After a month of pulling and prying my driveshaft finally came out of my crankshaft. It was stuck, really really stuck. Whether is was rust, carbon build-up (from overheating and burning any grease that once lubed the shaft), or just the previous owners neglect of this old beauty nobody will ever know, but a third round with the torch (following the car jack, a slide hammer, upside down soaking and rightside up soaking) separated the two. I have read every recommendation on this forum and ultimately you just have to keep banging at it until you win. The driveshaft puller helped to keep tension on the connection during its many soaks, pb penetrating, seafoam, liquid wrench, atf/acetone. During the process the driveshaft suffered. It is scratched and scarred and worst of all, bent. It is at the machine shop to get polished up and straightened out while I am in the process of cleaning the splines in the crank and ordering the parts I need to put it back together.

I am using a wire brush and various penetrating products to clean the crank splines (right now it is soaking in atf/acetone mix).

I am thinking I will be on the water next weekend!!!

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Well, she is back together, fired up, no water through the exhaust, really hot in a really short period of time.

Plenty of water in the test tank, about 1/2 up the exhaust housing, no obstructions in any of the water passages, all new gaskets.

The diagnosis after almost two months of restoration is that the block is cracked...

Can anybody explain to me how a cracked block will prevent any water from exiting through the exhaust...???

Confused

 

[lindy46]

Re: 1968 Evinrude 40 hp Big Twin Overheating

The diagnosis after almost two months of restoration is that the block is cracked...

Confused

Who made that diagnosis? Is the key/pin which drives the impeller in place and is the impeller snug on the driveshaft? I've had aftermarket impellers which were loose on the driveshaft and wouldn't pump water.

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

The water pump was fully replaced, all omc original product. New key, Impeller, housing, grommets, etc. All seated properly. The impeller is functioning because upon start-up I did get some water that came out of the side exhaust housing/ lower heat exchanger nut (It should not have, but I didn't have the nut tightened down enough. Once tightened no more water from there, but no water through the exhaust either.

The mechanic that's working on it says it has to be a cracked block.

 

[kfa4303]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Hello again supagidget. I doubt that it has a cracked block if it's running. Thankfully, the water cooling system is pretty simple overall, so it can only be a few things. Assuming the impeller really is properly installed, then work you way systematically up the motor to the copper uptake pipe. Remove it and check that it is clear of any blockages and replace. Now take a garden hose with tapered nozzle and spray water up the copper water pipe under med. pressure. You should notice all of the water coming back out of the main exhaust port on the back of the lower unit. If you are not getting water out, then you have a blockage in the powerhead, in which case you'll need to remove the headgasket and/or exhaust plate to visually inspect the water passages. That's really all there is to the cooling system. If there are no blockages in the powerhead, then you're back to the impeller. Give these tricks a try and let us know what you find.

 

[ward cleaver]

Re: 1968 Evinrude 40 hp Big Twin Overheating

I would remove the t-stat until you get water moving. Just in case it isn't passing water. It is just a complicating factor that you don't need right now.

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

kfa: Already done. With lower unit removed and garden hose attached to copper tubing water discharged from the other tube and no water came out of the exhaust port. The head gasket and side exhaust housing / heat exchager was removed. No blockages in the water jacket. Head cover was cleaned thouroughly when I had it decked.

I ran the motor with the lower unit off with the hose on the water intake tube and alot of exhaust pressure was felt coming from the other water tube. Back to the impeller, its functioning...

Ward Cleaver: I replaced the t-stat early on but will remove for now and try to start her up once again...

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Not an aftermarket part. All original OMC. Trying to unload her now and repower with a new motor. It was fun while it lasted. I also need to get rid of the cable and pulley steering on the clipper. Which was redone during the attempted rebuild. As you can see from above there are a ton of new parts on the motor.

 

[tx1961whaler]

Re: 1968 Evinrude 40 hp Big Twin Overheating

I have had a 40 where the water pump plate was not seated properly to the lower unit. It was a saltwater motor and was crusty under there. It would not pump water until the plate and housing were Permatex'd down after making sure the mating surface was as flat as possible..

 

[1946Zephyr]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Well, before you give up on it, I would pull the powerhead and make sure nothing is clogged up. Sometimes corrosion and debris can clog of water passages and have you cratching your head. I't nothing uncommon for old impeller pieces to break off and get stuck somewhere.

 

[kfa4303]

Re: 1968 Evinrude 40 hp Big Twin Overheating

I agree. Don't give up yet. These old motors are dang near bullet proof and well worth the effort. I'm thinking there's a piece of impeller clogging up the works some where. If you could get the power head off, you should try blasting some compressed air through the water passages to see if that frees anything up.

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

tx1961whaler, 1946Zephyr and kfa4303:

Thanks for all of your input throughout this process. The entire impeller housing, plate, grommets, etc, were replaced with new OMC parts. Every port and passeage in the head were blasted when it was at the machine shop. I even attached a garden house to the copper intake and the water stream out the other tube. Then I started it with the garden hose on the intake and more exhaust than water came out of the other tube. No water through the exhaust and found a drip of water in the upper cylinder on the exhaust side.

 

[Dirtscooter]

Re: 1968 Evinrude 40 hp Big Twin Overheating

tx1961whaler, 1946Zephyr and kfa4303:

Thanks for all of your input throughout this process. The entire impeller housing, plate, grommets, etc, were replaced with new OMC parts. Every port and passeage in the head were blasted when it was at the machine shop. I even attached a garden house to the copper intake and the water stream out the other tube. Then I started it with the garden hose on the intake and more exhaust than water came out of the other tube. No water through the exhaust and found a drip of water in the upper cylinder on the exhaust side.

I hate to see this thread die out without a resolution. It's doesn't seem unusual though; I mean the poster often goes along confused, befuddled, and sometimes frustrated. Members develop an interest and begin to chime in, eventually becoming involved and certainly wanting to see the positive outcome. It's what draws many of us to the forum. In other cases members and of course non-members, are reading along hoping to resolve the exact problem on Maple street USA, where they live. So after 9 or 29 posts it just dies when some felt close to seeing the poster beat the odds, and maybe one or more contributor having the solution, whether just silently thinking it at home, or boldly posting it, ending the game< one point or two points.
All that being said I don't fault SuperGiget as she went above and beyond the call of duty, and showed the intelligence to cut losses, I certainly don't view her as someone who walks away from a challenge or who takes a beating lightly. But Wanted to enjoy her boat as much as she wanted to win the game.

And again "that being said" I find I must take up her challenge, and from here fight out this overheating puzzle on my 1964 Evinrude Big Twin 40.. My first challenge however is that I am new and too stupid to figure out how to start a new thread, or post, whatever it's called.
I gather it is unacceptable to just continue from here, but I have pretty much the exact circumstances as SuperG, so not sure why it would me.. Will someone tell me in a hundred words how to start a new thread?? than Hi All from dirtscooter aka a previously silent guy from maple St USA

 

[lindy46]

Re: 1968 Evinrude 40 hp Big Twin Overheating

I gather it is unacceptable to just continue from here, but I have pretty much the exact circumstances as SuperG, so not sure why it would me.. Will someone tell me in a hundred words how to start a new thread?? than Hi All from dirtscooter aka a previously silent guy from maple St USA

From the forum page, where it says:
Forum: Johnson & Evinrude Outboards
Look above that title and click on "Post New Thread" button.

 

[supagidget]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Dirtscooter, I wish you the best of luck!

 

[Dirtscooter]

Re: 1968 Evinrude 40 hp Big Twin Overheating

Dirtscooter, I wish you the best of luck!

As it is that SupaG is still in this thread I feel it legitimate to make this entry,

I'm the guy with a similar problem and we finally blew an obstruction out of the water-jacket..and got it cooling... but took it to the lake and just didn't have the power I expected at WOT. Plowed at 17 MPH on a 16foor aluminum lone Star It wouldn't respond well to being Richened on the high side. The max it would take without bogging down was about 5/8ths of a turn from seat.

An outboard mechanic said that running a Big Twin without a Thermostat could cause power loss at WOT for a couple of reasons. non-uniform temp of both cylinders or just too cool, but it didn't like more fuel mix?!

Ok I'm going to give another look to starting a new thread sorry