| Author |
Message |
LABryan
Unregistered guest
Posted From: 63.199.58.226
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 05, 2006 - 7:57 pm: | |
I left the generator in my bus running unattended. Came back after about an hour to find the squirrel cage fan which cools the compartment had failed, causing serious overheating. High temp shutoff must also have failed. Gen was still running but temp gauge was pegged at 240. I shut it down and have not tried to re-start. Assuming it does run again, what should I do by way of maintenance other than changing oil and filters and replacing coolant? Obviously I will fix the squirrel cage and replace the high temp sensor before restarting. This is an Onan 15KW run by a Cummins 3 cylinder diesel. Is it likely to be toast? Thanks.
Bryan |
Len Silva (Lsilva)
Registered Member
Username: Lsilva
Post Number: 35
Registered: 12-2000
Posted From: 71.29.24.79
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 06, 2006 - 8:55 am: | |
You won't know for sure until you get it back on line. I very seriously overheated my 5.9 Cummins in a pickup truck with no ill effects.
One thing I would do is to add a sail switch to the shutdown circuit.
Len |
RJ Long (Rjlong)
Registered Member
Username: Rjlong
Post Number: 1013
Registered: 12-2000
Posted From: 71.195.113.23
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 06, 2006 - 10:08 am: | |
Len -
A sail switch to the shutdown circuit is a GREAT idea!
A question tho - if the squirrel cage only cycles on and off as needed, how/where would you incorporate the sail switch? |
john w. roan (Chessie4905)
Registered Member
Username: Chessie4905
Post Number: 301
Registered: 10-2003
Posted From: 69.162.3.30
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 06, 2006 - 5:28 pm: | |
Does the coolant smell burn't? If it does, I'd replace the head gasket and have the head checked for cracks; if the head turns out to be cracked, check the cylinder walls for scoring.If the antifreeze smells normal, you got lucky. otherwise you'll not know how much damage was done.... OR just run it and cross your fingers |
David Hartley (Drdave)
Registered Member
Username: Drdave
Post Number: 675
Registered: 5-2005
Posted From: 67.78.176.54
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 06, 2006 - 8:32 pm: | |
Here's what I would do,
Flush the coolant.
Check all the hoses and connections including clamps.
Drain the oil and change the oil filter.
Add 1 qt of Lucas Oil and 1/2 bottle of slick 50 high mileage to the crankcase.
Crank her over and see if it sounds like full compression on all cylinders. ( hold the fuel lever closed ! ) Then look into the radiator filler for any signs of bubbles. If you have bubbles you may have a gasket blown or cracked head.
No bubbles? Give it fuel and crank it up, look for bubbles, leaks or anything odd. If it runs good and doesn't have coolant in the oil or bubbles in the radiator you may be just fine.
I have an Isuzu 4 cylinder that got critically hot twice and it still runs great after doing the lucas and slick 50 treatment. ( save the engine!! ) |
LABryan
Unregistered guest
Posted From: 63.199.58.226
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 06, 2006 - 1:11 pm: | |
Len- Forgive my ignorance, but what is a sail switch? In my application the squirrel cage runs continuously (or at least it is supposed to) while the generator is running. I like this because it I have less concern about exhaust leaking into the bus. My exhaust system is tight, but I'm paranoid.
Bryan |
Bob greenwood (Bob_greenwood)
Registered Member
Username: Bob_greenwood
Post Number: 127
Registered: 7-2006
Posted From: 65.141.24.222
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 07, 2006 - 8:26 am: | |
I would try to turn the engine over,no need to add all those expencive things if the inserts are welded to the crank,just try for one or two revolutions |
Marc Bourget
Unregistered guest
Posted From: 64.142.42.176
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 07, 2006 - 11:21 am: | |
A sail switch is used to sense whether airflow is taking place. The airflow pushes the sail in the direction of flow, when the flow stops, the sail returns to position and either opens or closes a circuit, according to the need. |
JR Lynch (Njt5047)
Registered Member
Username: Njt5047
Post Number: 49
Registered: 7-2006
Posted From: 69.132.238.127
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 07, 2006 - 11:05 pm: | |
If it's screwed, it's screwed. If the coolant is still full and not discolored, and the oil isn't burnt smelling, I'd change the oil and filter and fire that puppy up. If it sounds normal, has normal oil pressure, and doesn't blow the water out, you're good...probably. Even if the engine is damaged, you are unlikely to significantly further the damage by running it for a short period, as long as no obvious new knocking sounds...etc, are noted. If the engine attains operating temps and otherwise performs as it normally would, it is likely not damaged. As you say, it was running when you shut it down. May be that the overheat was just about to kick in. May wish to verify your temp gauge while you're at it. It should have blown water out at 240*...maybe it didn't get that hot?
If the bearings are welded...well, it ain't going to make a lot of difference in the outcome as long as you don't persist and chuck a rod thru the block. Low oil pressure would (should) shut it down before this happens. Probably be looking for a new (reman) engine if it shutsdown or is knocking.
A simple overheat switch (Clix switch?) attached to a fuel sol would cut the engine off if the compartment suddenly heated above normal. I'm surprised that the overheat systems didn't shut the unit down. The overheat shutdown system should be repaired as necessary immediately, if it isn't working correctly.
A sail switch has a small lightweight "sail" on an arm connected to a micro switch. You would have to create some sort of override or delay to get the fan going while the sail assumes a position of operation within the fan's airflow. Good idea...but the execution will add another layer of potential failure. Instead of the squirrel cage blower, could you find an automotive style electric radiator fan to supplement the cooling? They are a little hungry, but very dependable.
My dos centavos! JR |
Stephen Fessenden (Sffess)
Registered Member
Username: Sffess
Post Number: 644
Registered: 1-2002
Posted From: 67.142.130.47
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 08, 2006 - 12:39 am: | |
After an overheat the rings may loose their temper and wear very quickly. Symptoms: greatly increased blowby and harder starting. Also, possibly shutdown at high but not overtemp temps. I had the problem with a Yanmar 16 HP engine in a John Deere lawn tractor. It had been run low on coolant and then lost power over the next 25 to 50 hours. All it took was rings. The cylinders and the heads were fine. So watch for a change in performance for a while but don't panic. Your engine had a full radiator. Mine didn't. After the new rings it has been fine for years. |