Engine never warms up

[olebiker]

I did not know the pump would pump with out a shoe.

I guess making your own bypass for the water flowing from the pump would be the next step

In the old style pumps, a shoe is required to prevent backflow, the new pumps have a flat spot cast into the pump where the shoe would have been.
Thanks to all for the advise. Will keep trying and let you know what is discovered. Another thought I had is: There is small (1/4") hole in the tstat flange. My thought is with the amount of flow I'm now getting, this hole may be allowing too much cold water to flow through the stat not allowing the water in the block/head to ever heat up...Thoughts???

[marthur]

I have a RWC engine and the Moyer pump. My boat is on the hard in Little Current Ontario and the Great Lakes are COLD in June, when we launch. Some years surface temps have been in the 40's F, usually in the low 50's. Even with that cold water, the hole in the T-stat flange does not prevent my engine from warming up. I am using the old double action thermostat, BTW. (Thank goodness I bought a spare 10 years ago when they were cheap, I still have one in its packaging).

The suggestions I am reading so far are: control the amount of flow by restricting the pump output. Double check your t-stat (the single action thermostats are pretty cheap, you may wish to pick up a spare)

To that I will add try leaning out your carb and advancing your timing. That made a major difference in my engine temperature.

BTW, the cross over hose on my motor usually feels cool. But the hose coming off the manifold to the exhaust should feel warm when the engine warms and the manifold should be warm too.

[olebiker]

Today I put a small screw in the hole of the tstat flange and installed the tsate. Motor warmed right up then went to 190 when I shut her down. Pulled the tstat and it was wide open. While running, when the motor started to heat, I turned the bypass fully closed and that stopped all water flow out the exhaust. I then opened it completely and got water flow but still continued to heat. I pulled the tstat out and installed another one with the flange hole open and the motor immediatly cooled all the way down to cold and even with the valve fully open stayed cold. I'm perplexed. I know the stat opened since I saw it fully open.

[ILikeRust]

While running, when the motor started to heat, I turned the bypass fully closed and that stopped all water flow out the exhaust.

That makes me think you've got a complete blockage somewhere - either in the injection port on the side plate or in the jacket itself. When you shut the bypass valve, all it should do is force all the water to flow through the block, into the head and out through the thermostat housing.

Can you post some pics showing how you've got it all plumbed?

[olebiker]

Ilike Rust,
Thanks for the reply.
The perplexity I'm having is when running with the Tstat without the flange hole plugged, I close the bypass valve and get lots of water flow. When I put a bolt in the little flange hole and close the bypass valve, there is no flow. I just had the side plate off and cleaned everything I could reach, and it was very clean. I also ran water down through the tstat opening while the side plate was off, and water came out freely. ????? Where would there be a blockage that could cause that?

[Dave Neptune]

DMS (acronym)

olebiker (peddle or motor?), something is amiss. Please explain again how things were set when the water flow was stoped? Is the sideplate deflector still in place?
If you have all of the flow,flow is not the problem but how/where it is flowing is possibly the issue.
I would double check the pump number to confirm it is correct.

When you hit 190 did the water flow still "flow" as much?

Note, a 1/4 inch hole in the "bypass" would work about right if you were using no t'stat and not much temp would show until the engine ran at "cruise load" for a while. Perhaps restricting the "hole" and not "plugging" it may help or shed some light.

Dave Neptune

[JOHN COOKSON]

A piece of crud, such as a broken impeller vane, lodged in the 90* elbow just after the water pump acting as a flapper valve might be causing some of your symptoms.

TRUE GRIT

[marthur]

I am wondering if the temperature reading is misleading. If there is a bit of crud that reduces flow through the block, could the temp sensor be seeing more cold water than anything else? On my engine, the temp sensor is right below the thermostat.

A piece of crud, such as a broken impeller vane, lodged in the 90* elbow just after the water pump acting as a flapper valve

This happened on my motor. I didn't realize it until I rebuilt the water pump. The increased pressure moved the broken impellor blade and the motor came close to overheating. I caught it on the temp sensor and spent a very nice hour bobbing in the ferry wakes off Mackinaw Island until I found the culprit: ) I wish to emphasize that I replace my impellors regularly. The PO must have left one in a little too long, though, because what I removed was definitely a piece of impellor blade.

[Dave Neptune]

Influence

marthur, I did not get accurate temp readings running "WITHOUT A THERMASTAT" on mine until I rerouted my "BYPASS" return away from the "THERMOSTAT HOUSING" to the manifold instead. Now ALL of the water in the area of the sendor is from the "BLOCK". This may be an issue if the t'stat was stuck open but even than I would think it enough of a baffle to insulate the sendor form the bypassed cold water.

olebiker, you may want to try without the t'stat just to see if it helps.
Also confirm thast the flow out the exhaust is not fluctuating if you can.

Dave Neptune

[olebiker]

Thanks for all the input.
After exhaustive investigation, I've determined:
There are no restrictions.
There is a huge amount of water pumping through the system.
Even with the bypass valve closed, open or anywhere in between the water outlet (at the back of the manifold) temp changes very little.
The temperature is fairly uniform anywhere on the motor. I used a infrared temp sensor for an hour testing all different bypass valve settings. No hot spots. Water leaving the manifold got to about 86 degrees and stayed there. The head never got over 105 anywhere at anytime.
So, I'm going to leave the stock single stage tsat in and just run her.

[Marian Claire]

If you want a simple, sure fire way to run at "appropriate temp" remove the T-stat and set up a recirculation loop. IIRC that was the original A-4 set up.
Dan S/V Marian Claire Yeeha # 1000

[edwardc]

Thanks for all the input.
After exhaustive investigation, I've determined:
There are no restrictions.
There is a huge amount of water pumping through the system.
Even with the bypass valve closed, open or anywhere in between the water outlet (at the back of the manifold) temp changes very little.
The temperature is fairly uniform anywhere on the motor. I used a infrared temp sensor for an hour testing all different bypass valve settings. No hot spots. Water leaving the manifold got to about 86 degrees and stayed there. The head never got over 105 anywhere at anytime.
So, I'm going to leave the stock single stage tsat in and just run her.

This is most perplexing! It's almost as if the bypass valve (or the check valve) was stuck closed, forcing all the cooling water through the block all the time. But, based on your previous posts, that's clearly not the case.

Did you ever try removing the bypass valve & check valve, and installing a straight piece of hose from the tee at the side water plate to the bypass inlet on the thermostat cover, as John Cookson suggested? This should produce almost no restriction in the bypass circuit, causing most of the cooling water to bypass the block, and the engine should heat up quite rapidly. If it doesn't, it means you're not bypassing enough water for some reason.

Perhaps some pictures of your plumbing and your thermostat mounting will give us some clue as to what's going on here.

[Sammckay]

Thermostat

Thermostat is stuck open...

[JOHN COOKSON]

Thermostat is stuck open...

Been there. Done this. See posts #3 & 4.

TRUE GRIT

[olebiker]

Finally, heat!!!!

After exploring every avenue suggested, and some, I took the thermostat and plugged the 1/4" hole and drilled an 1/8" hole in the flange. The motor heated to 180 with the bypass fully open. Closed it about 5 degrees and.......wait for it! The temp dropped to 155-165 and stay there at cruising speed for an hour. I will monitor the temp but this looks like a solution to too much water flow. As long as the little hole doesn't plug, it should be good.