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One engine runner hotten than other

D

dbrahms

Contributing Member
"have one new 360 (10hrs&#

"have one new 360 (10hrs) and one old 360 (1500 hrs) in my 33' egg harbor. the new one is pegged to 160 degrees when running at 3200. the other runs about 20degrees hotter than that when running. At idle, it's almost the same. I'm wondering if old exhaust manifolds and risers on the old engine could cause build up of heat. Any ideas?

coolant and sea water are running thru the motor just fine."
 
"..."coolant and sea water

"..."coolant and sea water are running thru the motor just fine."

Maybe, maybe not. Look at it in simple, sceintific terms: Assuming the thermostat is working properly, something is not taking enough heat away. You have to first verify that the t-stat is okay, then find out what that "something" is: air in the system, a slipping belt, bad impeller or circulating pump, etc.

And don't let it go, for someday that "something" is gonna bite you

Jeff"
 
"I would not assume both tempe

"I would not assume both temperature senders are linear. You do not say how you read temps, so I will assume you are using the gauges. If there are no other symptoms of overheating, it might pay to remove the temp senders put the business end into hot water and measure the resistance from the electric tab to the case at several temperatures to be sure the resistance in ohms is close to the same. You can also verify the thermostat in the "hotter" engine opens at the correct temperature by putting it in a pan of hot water and seeing at what temp it opens. If the sensor and thermostat pass, I would look next at the exhaust manifolds and risers. If you have access to an infrared thermometer you can use that to compare temps to what the gauge says. Is there any evidence of steam in the exhaust when the engines are at cruising speed?"
 
"Ed - there is steam coming ou

"Ed - there is steam coming out of both exhaust ports (both engines) when cruising. It's not a huge amount but it's there. I didnt think it was the gauge since the engine that shows hotter temps on the gauge does produce a bit more steam. Since there is physical evidence that something is causing it to run hotter, i didnt think it was gauge. Also, i dont think there are themostats on these motors. when i replaced the stbd engine a few weeks ago, i noticed there was no tstat at all so i assume the old motor also has no tstat."
 
"I don't know what the oth

"I don't know what the others think, but based on your last post, I would be looking at risers and manifolds. I would also compare the flow rates on the exhausts just to be sure there are no partial blockages. If they are about even, I would take a look at the manifolds and risers. It is very hard to see manifold/riser problems as they are usually eaten away from the inside out."
 
Steam is usually a sign of the exhaust manifolds getting to hot, although at this time of year steam is usual, can you put your hands on the manifolds when your running?, as for the engines, try cleaning the temp sender on the high hour one, might be dirty
 
Last summer my port 440 was engine was steaming pretty bad. I replaced the thermostat, manifolds and risers, impeller, and all cooling hoses and still had the steam problem. I also checked both of the heat exchangers for old impeller ribs, they were clean so I replaced the only thing left "the raw water pump housing" and viola, no more steam:) After I removed and inspected the raw water pump I could see that the ends of the pump had grooves in them and this prevented the pump from pumping enough water through the engine and risers.
 
redpaint said:
That's exactly how mine is. I just thought one motor has a 160 and the other a180 degree Thermostat. Running at 180 is OK.
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I have a similar situation on my 1974 440's @3200RPM. I suspect two different thermostats. Anyone know which is the preferred thermostat temperature to be running with these engines (part number would be a blessing too).

Thanks
 
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Is one of the engines hooked up to the hot water heater or a cabin heater? Have you verified the actual temperature with a hand held laser thermometer?

Dan
 
tolly_family said:
Is one of the engines hooked up to the hot water heater or a cabin heater? Have you verified the actual temperature with a hand held laser thermometer?

Dan
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Guess I should have given more info on first post. No, no hot water heater or cabin heater connection on either engine.

Yes, shot the port engine at about 167 degrees with laser therm, which is within 5 degrees of console gauge. Stbd engine shots with laser therm at 189 which is also roughly within 5 degrees on console gauge.

For a little background info: engines are on a Trojan 44 MY which I have had only about a year. There were many problems with the boat when I boat her, which would aloow getting up on a plane because of a seriously quirky trim tab problem. Recently, had most problems resolved in the yard( trim tabs, new risers/manifolds, clean running gear and bottom), and have gotten the thing up on a plane, but within 5 mins or less, that Stbd engine temp gauge gets up in the 180 area, so I've been getting chicken and pull her back and cruised around in the 1700 rpm range (don't need to be burning 32 gph anyways). Still I'd like to be able to know I could cruise longer distance at planning speeds if I wanted to (or could afford to) without worrying if I am doing any damage from higher temps.

Previous owner had his own mechanic with whom I had some dealings post-purchase. He appeared a bit of a muscle car man in background, and I doubt really a marine mechanic. Previously I can tell from reciepts he used a good deal of NAPA autoparts on the engines. And yes, there was record he had chaged the port engine with a 165 degree thermostat (no name brand given) back in 2000 and the Stbd engine got a new 160 degree thermostat back in 1999 (also no name brand in records). It may be he incorrectly recorded his repairs.

I did a little research last night from some manuals. Seems these fresh water cooled engines were supposed to run with the 180 degree thermostats, and engine temps may get up to 200 degrees. Am I correct? It just strikes me as being hot, but I guess it is not.

Maybe because of the age since last change, it is just time to change both and be assured the correct thermostats are in both engines once and for all. Any comments on using the NAPA thermostats vs. the marine versions I saw on http://hurrikain.com/

Thanks

Sean
 
Dont waste your time with the napa thermostats,they arent the right ones

Hurrikain is the right size about 2 7/16 round 160degree FWC
140degree for the raw water cooled
Also sierra can get them

180 is fine under load let that baby stay warm she aint no polar bear

160 to 200 degrees for FWC thats out the book you got another 20 degrees to burn

I would like to know at what speed do you reach plane about 1/2 tank of gas with 1 18 pack and a few sammies
 
greasemonkey said:
I would like to know at what speed do you reach plane about 1/2 tank of gas with 1 18 pack and a few sammies
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Appreciate the thermostat advice.

As for speed, Interestingly when I went out last week, I had exactly the half tank of gas (estimate about 180 gallons on board), though no Sammies, but maybe a 6 pack. However, I was heavy on water-just filled up-maybe 90 gallons or more on board.

Anyways, at cruise speed of 3200 rpm, GPS was running steady 14.75 kts though it flickered up to 15.25 kts a few times. In the past, I have guessed 15.25 kts is the steady speed at 3200 rpm's, but that's with less water on board.

BTW, this last time in yard, had the dual Flow-Scan unit installed. At the 3200 rpm, each engine looks like she is sipping (or gulping) 16 gallons per hour, perhaps slightly less, (maybe 15.5). regardless, that's still 30-32 gph, and something I won't be doing too often, as it comes out to less than 0.5 miles per gallon! Ouch to the wallet.

Thanks again, for the info.
 
That sounds just a tiny bit slow for those RPMs. My 40' Jersey Dawn runs about 17 kts at 3200rpm. Will you motors reach 4000RPM wide open? It should.
 
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