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1986 Johnson V4 140 Looper - Overheating problem

TipDS

Contributing Member
This engine came on a boat I bought a few months ago. It originally had no temp gauge. While out, we got clogged water intakes & the thing overheated and shut down. Never an alarm, or any other warning.

Since that time, I have (of course) cleaned the intake & also replaced the water pump. About the same time, I installed a temperature sender and a temperature gauge. Last outing, I noted the engine got to nearly 200 degrees F. The engine ran ok, but the temperature concerned me. Later, in an effort to track down why the engine was getting so hot, I pulled the thermostat covers to discover... there were no thermostats installed!

I read conflicting opinions about running without thermostats, including several that said the engine, especially the top cylinders will overheat without the thermostats restricting flow & allowing the water jacket to FULLY fill with cooling water.

I ordered new thermostats and gaskets. Installed them today & gave a test run. I quickly went OVER 200 degrees F, so I shut down.

I know water is flowing. The engine "pees" out the report hole. It was a weak-ish stream before, but very vigorous after installing thermostats.

What's the deal?
 
Temp gauge accurate?

Probably not down to the degree, but plenty close. The engine is DEFINITELY overheating, and badly. I don't have any melt sticks, but I'm 100% sure that both the 140 degree and 170 degree stick would melt PDQ, as hot as the block & heads are getting. Too hot to touch.
 
Ouch! Lets ask Mr. Reeves, he has good experience with saltwater motors......among everything else......surely our most experienced tech here.
 
What did you do to clog the intakes??? If mud/sand its in the block now also. Also is the water diverter valve still attached to throttle??
 
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What did you do to clog the intakes??? If mud/sand its in the block now also.
It was mud alright. I didn't think it was ingested, as I seem to get a pretty good water flow & the engine telltale is outputting. In fact, when I was installing the thermostats, I cracked one of the hoses that goes between the two thermostat covers... not badly, but just a tiny crack. When the engine was running, water was spraying out the crack about 2' long. Even so, I am overheating, so I don't mind double-triple-quadruple checking. If I was going to check for- or clean out- mud in the block, can you recommend the best method?
Also is the water diverter valve still attached to throttle??
Water diverter - Is that the same thing as the 0394407 "CONTROL VALVE ASSY"? I am pretty sure I do have it. I can take a picture, if that would help.

All this said, I'm going to re-do the water pump, as I'm not 100% confident I did everything perfectly. I didn't have the gasket glue to ensure the "o-ring" stayed in place on the housing, while installing over the impeller. (I had assumed that a small amount of leakage wouldn't make a huge difference either way. I can hardly imagine it would make the difference between running <170 degrees and running >200 degrees, but I'm willing to check/try anything, as I think this is a great little (and very light for the power) engine.

If you can think of any other things I should check, I'm all ears.

Thank you guys SO much. I appreciate your time and help a great deal.
 
Ok, today I re-did my water pump to ensure EVERYTHING was done 100% right - no fudging. I bought a whole new pump kit & replaced ALL the parts, used the correct grease, glue, sealer, etc, as prescribed in the service manual. Still over heating. Water is flowing, no doubt, but still overheating badly. After a brief test I decided to remove the thermostats, as the previous owner had done. While I had the thermostat covers off, I wanted to triple check the water was flowing at that point, so I started the engine again. In doing so, I noticed some smoke coming out. Hmmm. Replaced the thermostat gasket (without the thermostat) on each head & fired her back up again. Yes, still overheating.

Someone tell me it isn't what I'm thinking. Bad head gasket? If so, please tell me it's not a bad job. Also, does this more likely mean something is warped?
 
Could be some compression leaking into the water jacket, thereby disrupting water flow. A compression test MIGHT show where to look. Then if you find a bad head gasket, you might consider replacing both. Resurface head if needed, blocks will rarely warp, if they do, you have REAL problems.
 
Could be some compression leaking into the water jacket, thereby disrupting water flow. A compression test MIGHT show where to look. Then if you find a bad head gasket, you might consider replacing both. Resurface head if needed, blocks will rarely warp, if they do, you have REAL problems.

Forgive my ignorance, but I'm sure no outboard mechanic... I don't understand how compression would leak into the water jacket, except through a blown head gasket or through an actual hole in the cylinder. Is there another path for the combustion to access the cooling galleries?

(BTW: I just had to get the heads on another engine welded, because they HAD corroded through to the cooling water! $$$$) :-/
 
Right, head gasket leaking a small amount of compression from combustion chamber/cyl. to the water jacket. Produces bubbles that restrict proper water circulation.
 
So did you get things solved, brother? Salt can do some nasty things. I just had to repair a broken/rusty front subframe on the wife's "new" 2007 Dodge Caliber. It is now stronger than new. These subframes are really nothing more than conduit and laminated sheet steel. What are these engineers thinking? Its not like the US doesn't dump........this is salt alone, not considering enriched deicers like calcium chloride......10 Million TONS PER year, on America's roads.......go ahead, Google it up. Its like.....da! Why build stuff to last any longer than 10 years. I run 4 different old Johnson trolling motors at camp. ALL of which have the ORIGINAL water pump impeller. Why?..........quality..........Should I put a new impeller in? The new ones go 10 years max, then they crack apart, huh? Rubber now it too much synthesized. New tires crack apart in 10 to 15 years if you use 'em or not. Now isn't that great engineering? My trucks on the 1 mile portage in Ontario, have all 8 original tires on them......since 1982. Never even had to add more than a "breath" of air. Park them on wood boards in the winter........they have been exposed outside for 36 years. Now THATS quality, brother. I believe that there are good engineers out there, like those at CDI. They are using technological advancements to make electronics more trustworthy, as well as compatable. I trust them over OEM.
 
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Likely you have clogged passages in the cylinder head area from corrosion over time. Buy this infrared temperature gun and test the areas http://www.marineengine.com/boat-fo...-Thermometer-Temperature-Gun-a-Must-Have-Tool

Also see this Yamaha posting of mine: http://www.yamahaoutboardparts.com/...-forum/25719-wot-overheat-94-prov-115hp/page2

P.S.- I have had to clean the heads on 8 out of 12 used outboard engines I have had in the last 7 years, all the ones I've had to clean were Florida engines, salt water. Do not mess with the exhaust housing cover, I have never had clogging there and there are a ton of screws that will break!
 
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I believe that there are good engineers out there, like those at CDI. They are using technological advancements to make electronics more trustworthy, as well as compatable. I trust them over OEM
Since they have outsourced their quality has plummeted....wont use em anymore unless I cant get it from OEM or Serria. They where making them for BRP for 2 years but that got dropped due to...... take a guess?????..
.
.
.
.
.
.
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.quality!!!!!!!!!!!!!!
 
It will overheat without the t-stat/poppet. The water valve works in combination with these to allow them to unseat at RPM. The heads will run on the hot side externally due to they very little flow thru them. Check valve to see if water is being switched thru it as if not the poppet wont fully unseat and run hot. Check the alarm to see if working.
 
Thanks for all the input on this issue. Just as an update... I have ordered head gaskets and plan to remove the heads over the next couple days to examine the seal & any potential clogging of the water jacket, as well as the water diverters. I am now sure the water pump is at- or near- 100%, so that is not a problem. I'm going to apply PB Blaster to the head bolts tomorrow and hopefully tomorrow night, or the following day, I will put the impact wrench on the head bolts (low power to start) and see if I can't get inside to see what I see.

Thanks again for y'all's input and support.
 
Wow, Pappy. I never knew of CDI's quality issues. The older parts from them I have installed have run well over the years. I have had no returns. This past year I have been 6 months in the Philippines, so not much marine work here in USA. My experience with new CDI parts really dates back a couple years now, maybe I shouldn't brag them up. So you recommend Sierra now? I have used lots of Sierra since my return to USA in June and no CDI, reason being no electrical repairs where I didn't already have what I needed.
 
I use Serria when I can as since I am a dealer, an get that lifetime warranty as they will pay me for repair if it fails!!
 
This morning I got into the starboard head (and the one with the temperature sender in it.) Here's what I found:
IMG_20181031_140002.jpg
 
OK, I could only do the single picture, so...
IMG_20181031_135853.jpg
IMG_20181031_135859.jpg
OK, it must have been the picture size. Shrunk by 50% and they worked.
Anyhow, it appears the diverters are missing. Possible cause? Also, is there a reason (besides the obvious) that the head is marked with the text depicted???
 
Throw away the head gasket and scrape clean all the water passages with whatever fits in there (screw drivers, wires, bottle brush, broken glass....) When you are satisfied with the cleaning, put on the head gasket, torque on the head and you are ready to go test it. That should do it.
 
It says "sealer" under the do not use. Just cant read it well with the crud that's built up.
Thanks for that. After reading your comment, I looked closer & saw the rest of it. Whew - I was worried some idiot had installed factory rejected heads! LOL

Throw away the head gasket and scrape clean all the water passages with whatever fits in there (screw drivers, wires, bottle brush, broken glass....) When you are satisfied with the cleaning, put on the head gasket, torque on the head and you are ready to go test it. That should do it.
I'm going to give that a try, but I think I'm also going to put in some diverters. I'm thinking the missing diverters was my primary problem. I believe missing diverters allow the water to come in & go right back out, without having to complete a circuit, past the upper part of the water jacket. If I'm wrong, I hope someone will correct me.
 
What diverters are " missing " on this engine design ???-------As in are you sure diverters are used in these looper blocks !
 
What diverters are " missing " on this engine design ???-------As in are you sure diverters are used in these looper blocks !

Damnit! Now you have me unsure. I THOUGHT diverters were needed in all the V4 engines. What do you know that I don't? So far, everything I've seen says there should be two diverters on each side of the block.

Here's what I have from the service manual:
diverters.png
 

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The head gaskets pictured in post #25 do not look like V-4 looper head gaskets.-----If you are working from the wrong manual then what can I say ?
 
Well, SOB, someone get me strait. Are there separate diverters for the head and for the block? I'm no pro (probably very obvious, at this point) & am just trying to figure out this overheating issue. I thought I had found the issue with the "missing" diverters, but maybe not. Here are some images of my block, head and head with the gasket on. Can anyone help me figure out what engine I have (if it's not a looper) & where (or if) the diverters should be installed?
Block.png
Head without Gasket.jpg
Head with Gasket.jpg
I don't mind cutting and installing diverters for both the heads and the block independently, I just want to make sure I do it right.
 
Well,-----What does your factory manual say ?-------And does a parts breakdown of your motor show any diverters ??????------Note---- those head gaskets in post #25 are for a " crossflow " engine and you are working on a looper style engine.----Totally different machine.
 
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