TOPIC: thermostat question

After surfing the web awhile I found that the picture I posted is not the thermostat. It's the vernatherm? I'll check its operation and go from there.

I think "Vernatherm" is OMC's term for thermostat, if memory serves me correctly. I soaked mine in WD-40 and got it freed up, checked out fine after that. What are you missing, the spring and plastic valve? I'm not very knowledgeable on the Fat 50's, but we have a few who are and maybe even somebody who can help out with the missing parts?

(I wouldn't think that would stop it from pumping at all, should just let the water circulate through too quickly on warm up.)

Thanks Mark.

I checked the operation of the Vernatherm and it is good so i put the assembly back together. I thought i was missing part of the thermostat until i found out the vernatherm is supposed to look like that...i do have all my parts.

I removed thermostat assembly and checked water flow through cylinder heads etc and it's all flowing great.

i either installed impeller wrong even though i followed the instructions in my Seloc and Clymer manuals or the tube grommets might be too worn to seal the tubes and let the impeller do it's job? I don't know...just a guess.

OK. I looked into it further and really do not see what is causing the "no flow" water condition. All passages seem unclogged and i can use a water hose and run water through them all. I studied both of my manuals and am stumped. Any ideas before i lay this motor to rest and get the Mercury 500 i have my eye on?

Have you re-checked the condition of the water pump impeller? Kinda sounds like it may have "spun the hub" to me. (The inner part of the impeller spins but the "vanes" of the impeller don't). Key and keyway still intact? (Between the impeller hub and the driveshaft.) If all the passages are clear, water tubes and seals are as they should be, it's the only explanation I can think of.

I opened the water pump a little and spun the lower unit by hand and saw the new impeller turning so the key is good. Are there any bushings, o-rings, or other seals that should be replaced other than the 2 that are in the lower unit for the 2 tubes? I'm off to do more reading out of the manual.

Curse, does your motor have the copper tubes and if so are they solidly connected up in the exhaust housing and going into your water pump housing and water pick up securely? And also what about the water pick up passage?Could it be stopped up ? I had one of the copper tubes to break up inside my exhaust housing and caused an overheat. Just a thought. DUH,I didn't catch you last post about the "2 tubes" sorry

Curse, ditto on what Jim said, those copper tubes can be a b---- to realign in position. I'v had to re-do those things many times. it's easy to think you have them lined up with the rubber grommet thingies but when you bolt the lower back on all you do is push the tube up into the power head. Flashlight and thin wire/screwdriver will help position them.
Cal

I found on my 62,you can see the tubes as they make contact with the proper holes looking up through the exhaust exit with a flashlight shining through the side. I use a floor jack to lift it "very slowly". When I installed a new water pump on my 62,I noticed one of the tubes was bowed like a rainbow and not going straight into the pump housing. I took a 1x4 and used it to straighten the pipe.I checked it real good because I didn't want any issues with this engine having just had one of the tubes break up inside on the 63 johnson. Best'O'luck, jim

Heres one way to check to see if the water pump is working. You need a big half in drill and make up a way to put it on the drive shaft to spin it with the lower unit in water and if water comes out the tube its working. If no water it something in the pump Or the pickup is plug with sand or mud.
Mike aka the pirate

Thanks for the replies. I'm waiting for some parts i ordered and will try the drill.

This may be an overly simplistic question, but where are you running the motor? Is the water pump well submerged before starting the motor?

You are sure that both valves and springs are in the thermostat, right?

And finally are you sure it isn't pumping? They will only put out a fine mist till the thermostat opens. And with a good pump and plenty of water supply, it may not open at all at idle speeds

If the answer to all these is ok, then I'd suspect a leaks somewhere that is letting exhaust or air into the return water tube.

When i found it wasn't pumping i was at the boat launch. I have a 55 gallon drum that i cut the top 1/3 off. when it's full the lower unit is submerged quite a bit.

Yes both valves and springs are in the thermostat, i thought about removing them and the vernatherm to see if flow is better.

I'm pretty sure it is not pumping. I used a hand-held laser temp gun and shut motor down when it read 200 degrees. The temp gun seems pretty accurate and for the price it better be!

I've never removed the inner and outer exhaust covers to see what's behind them and the manuals don't make it clear but there are gaskets there that could be bad.
#25 in pic

another pic

My Clymer manual says there are water passage restictors on the V4...is this correct or does the fat 50 not use them? Mine does not have any so i assume this year did not use them.

I'm waiting on new head gaskets before i can check impeller operation with the vernatherm removed.

I got a 1961 Mercury 500 but it is a long shaft so i will most likely part it out. I also got a 1959 Mercury mark 35ae and thought about putting the 35 on my boat but i'm feeling quite attached to the fat 50. I guess i might end up removing the inner and outer exhaust covers to see if there is an issue there.

Do the cooling tubes attach to the exhaust adapter under the powerhead? The manual isn't real clear on that and the tubes will not remove from the top end of motor.

curse wrote:

My Clymer manual says there are water passage restictors on the V4...is this correct or does the fat 50 not use them? Mine does not have any so i assume this year did not use them.

Anyone? I need to know before i replace the head gaskets.

quote-(Do the cooling tubes attach to the exhaust adapter under the powerhead? The manual isn't real clear on that and the tubes will not remove from the top end of motor.)
Yes, each tube attaches to the
adapter assembly with a collar held on with two screws. I have a 75 hp apart now if you need some pics, let me know .jim

Jim, a few pics would be great. It might help my diagnosing if I can see what I'm dealing with. Do you remove power head as a complete unit or piece by piece? Thank you.

Jim, a few pics would be great. It might help my diagnosing if I can see what I'm dealing with. Do you remove power head as a complete unit or piece by piece? Thank you.

Here you go curse. Keep in mind this is a '63 75 hp electric shift,but other than the linkage verses electric cable, I'd think they would be very similar.

These motors can lose water pumping ability if a head gasket is leaking or blown. Exhaust gasses leaking into the water passages can blow all water out of the block.

Most Definitely pull both heads, check them for flatness and replace head gaskets, before removing the powerhead.

Another thing you can try is, with the lower unit removed, pipe water from your garden hose up the water supply tube and run the motor. Be very careful as you'll have little backpressure and she'll rev up fast (not good for V4's).

If you run enough pressure to get water circulation thru the block, it's gonna point out a leaking gasket (you'll get water on the offending cylinder's spark plug).

Your water system's pressure is enough to overcome any exhaust gasses blowing back into the water passages; however the motor's water pump won't develop enough pressure to do the same.

Note that leaking exhaust manifold gaskets can also cause water-pumping issues, but blown head gasket(s) a more common cause of this problem.

I can't recall any rubber flow diverters in the old V4 blocks, they definitely had them in later models. If you pull both both heads and find no rubber bits in either side, I'd say you're pretty safe in assuming there are none. On blocks which have the diverters, they slide into grooves which are designed to hold the diverter in place.

HTH & G'luck with the troubleshooting.........ed

Thanks a ton for all the replies and pics.

This may turn into a winter tear down to find the problem!

Update.

I took lower unit off and was looking everything over when i found the water tubes are loose (they twist/spin easy and one of them can be moved at least an inch) and may have something to do with the water not circulating?????

Question is..is there an easier way to get the powerhead off the top of motor? I got the lower tray/cowel loose but it is still in the way of the bolts at the bottom of the powerhead. Is it really a pain in the butt or am i missing something?

Actually not that difficult - once you know how. You need to undo the motor from the rubber shock-mounts, upper and lower. Once those are loose, the exhaust housing (with powerhead attached) will come free of the outer housing & clamp bracket assembly. Make sure all hoses, wires, etc. from powerhead to lower pan are undone. Once the powerhead/exhaust housing assembly is free of the mid, all the bolts and nuts will be accessible.

I got it apart, it was a little different than described but it is apart. Could the exhaust gasket out of place be an issue....i don't see how that could affect water flow but???

sorry...double post

I will assume the gasket is possibly my "no water pumping" issue.

I'm going to replace the Inner to outer exhaust gasket, water tube grommets, Adapter to outer exhaust tube gasket, Adapter to powerhead gasket, and head gaskets. I was going to replace adapter to coupling gaskets but cannot locate replacements and will probably make some.

1. Anything else i should replace or look into while it's apart?
2. are water tube grommets usually replaced or reused?

Boy - this has been a saga for you hasn't it? I'm sorry I missed this post for so long - I have a lot of time (too much) with these engines under my belt. In fact, I haulled 750 Lbs of old V4 parts to the scrap yard last thursday. Not to worry - I have many more.

The exhaust donut is important, but would not prevent the water from pumping. It mainly helps to prevent exhaust gasses from getting up to the "fresh air" side of the powerhead. Suspect leaking supply line seals at the powerhead adapter plate. This is where the two pipes attach to the plate with 2 screws each. If the engine has been run without water, the intense heat can destroy the seals at the mounting boss very quickly. Quickly will runi the rest of the motor too.
Keep in mind - one of the copper pipes is the fresh water supply line, and the other is a hot water bypass line. The thermostat will send pre-heated water back down to the water pump until the thermostat opens. That is why there are two pipes - the water "loops" until it needed for cooling. When the engine is warm and the thermostat fully opens - a fair bit of water will be exiting the exhaust bypass port IF the engine is in water deep enough to cover the bypass plate on the lower unit. This is the plate that is on the left side of the engine - just below the water pump housing. If the engine is being supplied by a hose and the lower unit is dangling in air - don't expect to see much, if any spray from the bypass port on the rear tower cover.

All this aside - please seriously consider a suggestion? If you want to keep the Fifty because you like the way it looks, you can "cheat" a little to get a much better engine, while maintaining the original appearance. Since you have the engine completely apart right now, you have an excellent opportunity to put a later powerhead on that motor. Or even better - get a later 75hp -85hp engine and put the cowling pan and hood from the Fat Fifty on the newer motor. The bolt pattern, physical size, weight, appearance, and sound of the V4 engines remained nearly identical up to 1968.

If you look at the benefits from doing this - it's sort of a no brainer. The Fifty was pretty much a POS right out of the box. OMC knew this was the case, but the were racing to close the HP gap with Mercury. The Fifty was twice the size of the OMC 35 hp, while only making 15 more horsepower! It even drank twice the fuel of the little 35hp. The reason there are so many fat 50s still in good shape is because people got them off of their boats as fast as they could afford to do so. The 1960 75 HP V4 was a bif improvement of the 58 Fifty. It made 25 more HP, but actually had better fuel economy. Don't get me wrong - it still drank gas like no tomorrow, but it was thrifty compared to the Fifty. If you can find a decent condition 75hp-85hp Johnson or Evinrude from 1963 to 1968 those had the best durability and performance of the early OMC V4 design. Either plop a powerhead from one of these onto the Fifty, or put the Fifty cowl on the later engine. The transom brackets and lower units of the later engines are far superior to the Fifty, so a simple pan & hood swap is the smartest way to go. Only you will know that you have changed the motor, until your friends wonder how a Fat Fifty can push your boat past 40 MPH.

everything useses same bolts, spacing, driveshaft etc. Bolt-on swap - no other modifications at all

Bruce, that post I printed. I haven't gotten to my 100hp Johnson gold meteor '69 yet, probably won't for awhile yet since I'm still working on the boat but I did put in a new impeller and starter solenoid but never ran it. PO said it had cooling problems and needed a new impeller. I'm stashing that post for reference.
Cal

Wow! Thanks Bruce, that was some great info.

I think i"ll put my mark 35a on the boat for now and look for the 63-78 75-85hp. I looked everything else over and it all seems ok...nothing visually bad. Will i re-use the exhaust adapter or replace that along with the powerhead from the newer motor?

One question, if my boat is rated at 50hp is 75hp going to be ok?

Thanks again.

If your transom is good and soloid it shouldn't be any proublem. If you don't think its strong enough you can beef it up some.
Mike aka the pirate

Good, the transom is rock solid.

I have a lead on what might be a 1962 75hp starflite. I haven't seen it yet.

Bruce, you said to find a 63-68 75hp. I just want to make sure a 62 is good??? (anybody's opinion welcome). By the way it is a long shaft so i will need to use the lower unit from the 50.

Anything after 1960 had improvements. The Fify picked up 10 horses with new reeds, improved carb, and improved heads. The 75 made it's first appearance. Along about 1963 /1964 the engines were built with much stronger connecting rods and rod bolts. At some point the johnson & Evinrude V4 engines were upgraded to 80 hp, 1967 saw the introduction of a new light weight under-flywheel alternator. It did not require a regulator box like the old "unicharger" system did. 1967 was the last year for the belt driven distributor.

1968 was the final year of the Generation I block. The belt driven disto was dropped and ignition was moved to under the flywheel. The flywheel was changed, as was the crankshaft snout. The 1968 flywheels can not be used on earlier engines - nor pre '68 flywheels used on a '68 engine. The throttle lever arrangement was vastly improved. Horsepowers for 1968 were 65, 85, 100, and 115 for the awesome X115 and GT115 racing engines.

1969 was the introduction of the type II engine that had the new crankcase with two side draft 2 barrel carbs. This design would last to the end of cross flow V4 production in the 1990s Unfortunately - the footprint of the powerhead flange was changed, and it is not compatible with the earlier towers.

Ok. i'll get the model number and see exactly what it is. Thanks.

Ok, here is the motor i found. Owner thought it was a 90 hp but i got the model number (80793 r) and see it's a 67 80hp. Since it is a long shaft i will need to use the 50 lower unit along with the hood from the 50. Another thing...i couldn't find a parts diagram at marineengine.com. Any links to other sites that do have a diagram?

Before i pay the $150 for it is this a good motor?

The Johnson equivalent is likely listed on marineengine.-Different cover and different colour paint.

The engine is priced good, but only if it checks out. You will need to do a compression test on all four cylinders. DO NOT shoot oil into the cylinders before testing them. Test each cylinder and record the numbers. All four cylinders should have similar readings. Anything more than 20% between cylinders usually indicates a major problem. A 10% difference is common and suggests the cylinders are decent. When new, this engine probably pushed 100psi per cylinder. Old but good running ones will often push 80psi per cylinder. Be absolutely certain that it is not a salt water engine. Salty engines will have rusted screws on the thermostat cover, and likely rusty cylinder head / exhaust cover bolts. Do not buy a salty engine. Forget the lower unit from the Fifty - it's a complete dog. Find a short drive shaft for the 85 lower unit. They are easy to come by, and simple to change. You will also need to change the shift shaft in the lower unit, and shorten the water pump tubes. It is all pretty easy to do, really. The lower unit must be disassembled, but it should have a seal kit installed in it anyway. If you go this route - there is plenty of help here if you need it.

I'm giving you a link to the BRP website parts database. BRP only goes back to 1968. But the 1968 Evinrude 85 HP speedifour was nearly the same engine as the 1967 80 hp., excepting for the flywheel, ignition, and internal throttle linkage. All other parts are same. Click on the link and use the pull down menues to search

epc.brp.com/Index.aspx?lang=E&s1=bc1e8d65-9924-4a11-b364-55ccabb78fc5

The 67 Johnson models ( different cover / paint ) are listed on marineengine.com.

Thanks guys.

Bruce Gerard wrote:

Forget the lower unit from the Fifty - it's a complete dog. Find a short drive shaft for the 85 lower unit. They are easy to come by, and simple to change.

Hey Bruce, in the quote above you said 85 lower unit. Where you talking about the 80hp i plan on buying or where you saying to get an 85hp lower unit for the 80hp?

I think i know what you meant but just want to make sure.