Evinrude 1979 V4 crossflow cooling issue.

[daselbee]

Hey guys...I need some advice...

I have this friend's engine 140943R (1979 140) that has had a powerhead rebuild. Ever since the rebuild, it has not cooled right. Specifically, it does not get hot enough. It runs at 110 degrees. It will never get up to the 140 degree thermo opening temp.

It has new water pump, stats, phead gasket...all that stuff.

I have no real experience with this vintage of engine, so I need to know what is normal with regard to the water ejected from the exhaust relief holes on the back of the leg.

First pic...right at startup, note minor smoking from ex relief holes. Note pee stream. WP is 15 psi.

Second: Five secs after startup, water begins to slightly spray from ex relief holes.

Third: Ten secs after start, water GUSHING from ex relief holes.

Fourth: From other side with lighting to show how much water is gushing.

The thermos never open (not hot enough) the poppets are in place with proper springs, where is all this water coming from?

Anyone have experience with something like this?

 

[DargelJohn]

Re: Evinrude 1979 V4 crossflow cooling issue.

Yep, That is way too much water coming from relief valve ports. Should only be a fine mist @ idle, even warmed up.

Only thing I can think to do is to go back through the thermostat housing and check all the parts. Make sure poppet valves are seating, rubber sleeves are in place (Red Arrow), springs are in place, and make sure those cork gaskets (Green arrow) are in place on the thermostats, everything is in the order. That being a bubble back, not the easiest job in the world.
Good Luck

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

Thanks DJ...I have started exactly that. Basically, I thought the poppets were wide open for some reason, so I tore back into the thermo housing. Everything is as it should be. Poppets, grommets, springs, thermos....all correct. So, as a test, I blocked the bypass poppets closed, and put the housing back. This would force the thermos to handle all the coolant flow.

I got the same result. Gushing water, and running at 110 degrees.

I really wonder about that 10 sec delay until the water starts gushing. Note that the pee stream is good and strong immediately, but the gushing starts 10 sec later.

Is it possible that the inner exhaust housing seals are missing? Is this leg filling up with water (10 secs) until it hits the relief holes then gushes out?
Is this a symptom of when those inner seals are leaking or just plain gone?

I have no idea on the history of the motor's previous repairs.....

 

[DargelJohn]

Re: Evinrude 1979 V4 crossflow cooling issue.

Did the motor have this problem before the rebuild?

You do have a paper gasket where the inner exhaust housing bolts to the lower section. It also contains the copper water tube (from water pump) with a rubber grommet. If that gasket failed, I don't think you'd be getting water to the powerhead.

110 degrees, the water is somehow bypassing the thermostats.

Another possibility is that maybe the powerhead base gasket is on backwards. Don't know if that's possible though.

 

[DargelJohn]

Re: Evinrude 1979 V4 crossflow cooling issue.

daselbee, After going back and looking at the base gasket (Red arrow), that could be the problem! The bolt pattern is such that someone could have put on, flipped over the wrong way.

If flipped over, the water passages would not be sealed correctly, causing who knows what....

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

TTT Bump, anyone else have any thoughts?

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

Update on this....
I just pulled the powerhead (V4 crossflow, 140), and found the brand new Sierra Phead to Ex. Adapter gasket in a "shredded" condition.
It was just absolutely torn up. when I put it together, I coated that gasket very lightly with Permatex aviation form-a-gasket, just enough to slightly wet it. It seems as if the Permatex has actually "lubed up" the gasket and it squished out into the exhaust hole, as well as other places around the perimeter of the ex housing.

Maybe I should have put this gasket on dry? (DJ, it was in the correct orientation.)

I am searching for a genuine Evinrude gasket in stock somewhere here near Titusville Fl, but no luck. Will re-install phead with dry gasket and see if the problem is fixed.
I will also post a comparison on the relative quality of the Evinrude gasket vs. the Sierra gasket.

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

For those interested, I got the Evinrude base gasket and compared the Sierra...

Wow, what a difference. The Sierra was 1 ply, .015" in thickness, and the consistency of newspaper.

The Evinrude gasket was 3 ply, metal center ply, and .045" in thickness. Three times thicker.

I put it on dry. Guess what? Problem persists. Not fixed yet, but I feel much better about the base gasket, and the thermos were SO easy to get on with the powerhead off. LOL. Pull the powerhead to do a thermo job...sheesh.

 

[emdsapmgr]

Re: Evinrude 1979 V4 crossflow cooling issue.

That's a good catch on the powerhead base gasket. The correct one is that Bombardier one which has a thick, metal appearance to it. That will withstand the heat and will last for years. Once the stats open, it is normal for that engine to pour some streams of water from the exhaust relief ports. That flow will increase further, once you get on plane. [The older OMC V4's that have only one stat are the ones that only spray a mist out those ports.] It is still puzzling that it won't heat up to around 143 when idling. Are you using a laser temp gun when taking your measurements, or the temp gauge in the boat? When you were in the stat housing replacing the stats, what condition were the nylon pressure relief valves? At idle, those valves are closed and all the water has to circulate through those stats. Usually, the engine will heat up to 143-145 when idling. Once you crack the throttle to a certain point, the increased impeller water pressure/flow can force open those nylon relief valves, and the increased water flow can cause an onrush of cool water which can cause the powerhead temps to go down significantly-even to 110.

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

Thanks Emd....Yes i use a laser temp gun. After the gasket replace yesterday, the engine now idles at 140. As I increase throttle, the temp does go down to 105 or so. That varies at different places around the heads. Back to idle, and the temp rises to 140.

So, you are describing exactly what is happening. This is good news to me. Sounds like this is good to go now.

Regarding the thermo parts, all are new, and checked and double checked by two ppl when I assembled them yesterday.

The problem is....I just don't know what is normal for water flow out those ports.

 

[emdsapmgr]

Re: Evinrude 1979 V4 crossflow cooling issue.

Sounds like your system is functioning as designed. Your temps should be right around where you are seeing them. My 79 85 hp engine puts out a lot of water from those ports at idle on the hose. When it is on plane, looks like two steady streams.

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

Thanks very much Emd....I have called it good and returned the boat to the owner today. He is gonna watch it. I know for sure it is NOT overheating, so I think I was trying to fix something that was not broken.!!!!

Other than the cheap phead to exhaust adapter gasket.... that was a good fix.

 

[tx1961whaler]

Re: Evinrude 1979 V4 crossflow cooling issue.

"In Stock" and "Titusville" does not compute.....

 

[daselbee]

Re: Evinrude 1979 V4 crossflow cooling issue.

10-4 on that one....Titusville is a dying town. Space center winding down, 5 year minimum hiatus on any NASA stuff....other than that GD "NASA is a liason to the Islamic culture to bring them into the Space Age" nonsense that Obama sent Charlie Bolden over seas to promote....
Feds are nothing but lip service at this point. Anyway.....

Nope, no stock on the Space Coast...I had to drive to Orlando to get that gasket. 1.5 hrs.