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| P-60 getting hot but not quite overhe... |
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Brent
Member
Username: brent
Post Number: 8
Registered: 03-2009
| | Posted on Monday, July 29, 2013 - 06:33 pm: | 
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Our P-60 is running a little hot lately, peaking at about 160-170 degrees before it starts coming down. She lives in salt water. Based on some searches I did here, I tried a few things:
1) Swapped the thermostat. No change.
2) Removed the thermostat. The engine actually got hotter (reached 200 degrees before we shut her down and replaced the thermostat). Tried this only once.
3) Removed the thermometer. This was most interesting. The water elsewhere in the system is clear, but here it is black. There's no oily or greasy feeling to it; it's just black.
4) Removed the air bleed line and checked the fittings. All OK here. There was some black crusty stuff (rust?) at the head side, but it was loose and easily scraped out, and the fittings and hose were clear.
5) Checked the water pump impeller. All OK here.
6) Checked the water flow. We've a Groco strainer between the seacock and water pump. I've opened the top of the strainer and verified a good flow of water here, and once the thermostat opens there's a good flow of water from the exhaust.
A couple of observations:
7) The Groco strainer has a bronze top and a clear plastic bottom. When the engine was running, I noticed some water leaking from around the joint between the two. Could this be backpressure? Water was coming out, but could it also be a source of air, perhaps preventing the pump from drawing in enough seawater?
8) When starting the engine from a cold state, I felt the hose from the thermostat to the exhaust. This didn't get warm until the temperature peaked and started to drop. It's suggestive of a bad thermostat, but I've several (I tend to use them for 1-2 years, buy new and keep the old ones as spares) and they're all rated for 140 degrees. I've had thermostats physically break, but can they go bad, opening at higher and higher temperatures as they age?
Because of the work involved, I've not yet removed any of the flanges or the head to check for blockages. Those are next on the list, but I wanted to get some feedback first, in case there's an easier fix here that I've missed.
Thoughts? |
Jim
Member
Username: jimct
Post Number: 17
Registered: 08-2007
| | Posted on Monday, July 29, 2013 - 09:27 pm: |
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Hmmm, sounds like a knotty problem there.
First off, I'd pull the hose off the discharge side of the water pump and briefly run the engine to be sure there is a good strong flow from the pump. Thumb-test the flow for pressure. if it's strong, then that's good.
Next, while the discharge hose is off the pump, I'd remove the thermostat "T" fitting which screws onto the top of the manifold and put a water hose in it and back-flush the engine. Watch the water pump hose for debris exiting. You will likely see some. Keep flushing until the water runs clear. Put the thermostat "T" fitting back on the manifold and reconnect the water pump discharge hose to the pump. Start the engine & see what happens.
If it still runs hot, and I know you really don't want to hear this, I'd pull the head and check the water passages between the head & the block. They can close-up enough with rust over time to restrict good water circulation to the head. Clean up the head and block mating surfaces, put on a new head gasket (copper in your case since you are running in salt water) and give her a try. My money says she'll be back to normal.
You can get a copper gasket here: http://www.gasketstogo.com/
He's an ex-pat living out in Thailand and runs a good shop and ships promptly. You might find a copper gasket state-side but still I'd recommend Gaskets To Go.
Keep us posted on how you do... that's how we learn and stay ahead of these old girls. |
Jim
Member
Username: jimct
Post Number: 18
Registered: 08-2007
| | Posted on Monday, July 29, 2013 - 09:32 pm: |
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One other thing I forgot; get the copper sandwich gasket. See: http://www.gasketstogo.com/Palmer.htm |
Eddie Ross
Senior Member
Username: eddie
Post Number: 314
Registered: 04-2003
| | Posted on Tuesday, July 30, 2013 - 10:50 am: |
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How old is the impeller in the water pump ? |
Brent
Member
Username: brent
Post Number: 9
Registered: 03-2009
| | Posted on Wednesday, July 31, 2013 - 06:56 pm: |
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Eddie, The impeller is new. I'd changed it when she first acted up, but the "old" one appeared to be as new.
Jim, I've not yet had the opportunity to try your recommendations (no garden hose on the mooring), but I did try a few things.
Her prior behavior suggested some sort of back pressure that might be inhibiting the hot water from getting expelled, so I removed the hose which runs from the thermostat to the exhaust and blew into the exhaust end. Some water was expelled. There was more resistance than I expected, but I'm not sure what is "normal" since I've never done it before.
After putting everything back together, I started her up and she proceeded to overheat, so I shut her down.
Then I restarted her. This is where it gets interesting. She was already a little hot, but I was now getting water out the exhaust and the temperature was dropping.
Up until this point, I'd kept her rpms low (500-800), but it occurred to me that if there's some sort of back pressure, perhaps more pressure - speeding up the water pump - would help overcome that. So I rev'd her up to 1400 - and the temperature stabilized. She wasn't under load - I was still on the mooring and out of gear - but I had a steady flow of water from the exhaust and the temperature was stable at about 130-140 degrees.
Once I get her off the mooring and open up the throttle, we'll see how she behaves. However, the thermometer hasn't looked this good in weeks, so I'm hopeful. |
Jim
Member
Username: jimct
Post Number: 21
Registered: 08-2007
| | Posted on Wednesday, July 31, 2013 - 09:33 pm: |
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The thermostat tells the tale. If it's happy everybody's happy. Back pressure from even slight blockages will certainly cause overheating. Impeller-type pumps are first-rate volume pumps but not particularly good pressure pumps.
When you blew into the hose leading overboard the back pressure you sensed may have been from the muffler (if you've got one). If there is no muffler then that discharge hose may be partially blocked or collapsed internally. Anyway, something caused the problem. When you lay-up in the off-season you might want to chase this down and see what's what. On our Palmer I added a low oil pressure/high engine temp. alarm. The alarm is a loud buzzer. The alarm relieves me from having to keep a constant eye on the gauges. |
Brent
Member
Username: brent
Post Number: 10
Registered: 03-2009
| | Posted on Wednesday, July 31, 2013 - 09:33 pm: |
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UPDATE!
Got her off the mooring and motored around for about an hour.
At about 1000 rpm under load the temperature is stable at 140 degrees. As we slowed, the temperature slowly climbed, but tended to be stable until we dropped to about 750 rpm, at which point the temperature rose to over 160 degrees.
Pulling her out of gear at this point caused the rpm to rise to about 2000 rpm, which seemed to give her a kick in the pants - the temperature dropped quickly to about 110 degrees.
At the lower rpm, the system was cycling, but the thermometer was reading 170-180 (and higher at one point) before it started to come back down again.
(Note that the temperatures are largely estimates; the only numberals are 60, 160 and 200, with tick marks at what seem to be 110 and 180)
I still have to test the thermostat to be sure that it's opening at 140 degrees, and do Jim's thumb-test of the pump flow. |
Jim
Member
Username: jimct
Post Number: 22
Registered: 08-2007
| | Posted on Wednesday, July 31, 2013 - 09:48 pm: |
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Thinking more about this, your engine's behavior mimics a sticky thermostat. From your post I can't tell if you've swapped out the thermostat with a new one or even an old one from your parts inventory. Might be an interesting test. Thermostats are flighty things. I've had new ones fail on two occasions.
When your wife is elsewhere, put the suspect t'stat in a saucepan full of water and heat it up on the stove. Measure the temp. of the water and watch for the thermostat to open at 140. |
Jim
Member
Username: jimct
Post Number: 23
Registered: 08-2007
| | Posted on Wednesday, July 31, 2013 - 09:56 pm: |
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Missed your UPDATE before my last post.
Something may be wandering around in your cooling loop somewhere which occasionally causes a blockage. Loose fragments of broken rubber impeller vanes are notorious for this. When you get to the dock again, I'd flush the hell out of the engine. |
Eddie Ross
Senior Member
Username: eddie
Post Number: 316
Registered: 04-2003
| | Posted on Thursday, August 01, 2013 - 10:37 am: |
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How long has it been since you replaced the hoses ? |
Arthur Zeman
Member
Username: art
Post Number: 8
Registered: 10-2007
| | Posted on Thursday, August 01, 2013 - 11:29 am: |
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Thermostat in backwards????? |
tim walker
Member
Username: i_fix_it
Post Number: 15
Registered: 11-2008
| | Posted on Friday, August 02, 2013 - 03:46 pm: |
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Hi Brent, Check your timing . If your timing is to retarded it would give all the sympyems youve thrown out to us . runs hot at low Rs,cools off at higher Rs, Rpm jumps when you take it out of gear at low Rs. When you rev it up the mechaincle advance kicks in and it cools off. Some times its the littlest things. Tim |
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