Overheating continues

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Ivory
Posts: 3
Joined: Tue Jun 16, 2020 12:13 pm
Location: Lake Wales Florida

Overheating continues

Post by Ivory »

1994 Serengeti Ivory, 8.3 Cummins, 150,000 miles, runs excellent.
I have been battling overheating for a long time I must resolve the issue to be able to use the mh in the summer. Previously I had been unable to travel very far due to caregiving responsibilities, now I can go, but not on a hot day.
I have replaced radiator with a new 4 row radiator rated for a Peterbilt. CAC has been removed and pressure tested and cleaned., 160 degree thermostats, new hoses. Added 3000 cfm electric fan (puller), OAT coolant, race car
additive. Engine fan is direct drive with new cog belt, water pump has been removed and inspected, engine cooling passages look like new.
Cooling system cleaned and flushed per radiator shop instructions. Fan shroud inspected by radiator shop for positioning.

Running 65 mph in Texas I -40 westbound, 93 degrees, slight head wind, temp gradually climbed to 220, pulled over.
(In cooler weather (mid 80's,) it will run 200-210.)
Removed rear grill, still had to pull off the highway.
This cooling system has been totally apart by freightliner and a year later a radiator shop and noone can see a problem (other than rear radiator design).
Injector pump has been rebuilt to spec.
I and my resources have run out of ideas.
What am I missing?
stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Re: Overheating continues

Post by stuplich@ymail.com »

Ivory wrote: Fri Jul 23, 2021 10:01 am 1994 Serengeti Ivory, 8.3 Cummins, 150,000 miles, runs excellent.
I have been battling overheating for a long time I must resolve the issue to be able to use the mh in the summer. Previously I had been unable to travel very far due to caregiving responsibilities, now I can go, but not on a hot day.
I have replaced radiator with a new 4 row radiator rated for a Peterbilt. CAC has been removed and pressure tested and cleaned., 160 degree thermostats, new hoses. Added 3000 cfm electric fan (puller), OAT coolant, race car
additive. Engine fan is direct drive with new cog belt, water pump has been removed and inspected, engine cooling passages look like new.
Cooling system cleaned and flushed per radiator shop instructions. Fan shroud inspected by radiator shop for positioning.
Running 65 mph in Texas I -40 westbound, 93 degrees, slight head wind, temp gradually climbed to 220, pulled over.
(In cooler weather (mid 80's,) it will run 200-210.)
Removed rear grill, still had to pull off the highway.
This cooling system has been totally apart by freightliner and a year later a radiator shop and no one can see a problem (other than rear radiator design).
Injector pump has been rebuilt to spec.
I and my resources have run out of ideas.
What am I missing?
Ivory,
Before the radiator/CAC sandwich on my rear radiator CAT powered coach was 1st cleaned, (at 78,000 miles), it would overheat and de-rate, (in 80 degree F and warmer weather), at any sustained speed above 55 MPH....

However another cause of diesel engine overheating can be a clogged diesel injector.
When an injector is clogged, the injector system does not release fuel properly, causing the engine to work extra hard and subsequently overheat...
See https://cdspros.com/top-8-causes-of-die ... erheating/
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
ProCycle
Posts: 135
Joined: Sat Oct 03, 2020 1:28 pm

Re: Overheating continues

Post by ProCycle »

It sounds like you've gone through the entire cooling system. It certainly should be up to the task.
Does it actually overflow coolant? Or does the gauge juts read too hot?
Have you verified that the temperature reading is accurate? A faulty sensor or gauge could have you chasing your tail on this for ever.
Like Mel says, there could be some other problem causing it to create more heat than the cooling system can handle.
A leaky head gasket could do this but it probably would be loosing coolant as well.
Jeff
1997 Ivory Edition 3740 Cat 3126 Allison
1Lotosrggp
Posts: 51
Joined: Sun Oct 27, 2019 6:08 pm

Re: Overheating continues

Post by 1Lotosrggp »

Diesels are heat engines, Put the correct thermostat back in it and check your gauge including ground wire. Just saying.
Tom
97 Sahara 3550
3126 CAT 300hp
ProCycle
Posts: 135
Joined: Sat Oct 03, 2020 1:28 pm

Re: Overheating continues

Post by ProCycle »

Absolutely. No way would I ever run mine with a 160 degree thermostat. It will be more efficient when it's running on the warmer side - as long as it doesn't get TOO hot.
Jeff
1997 Ivory Edition 3740 Cat 3126 Allison
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Overheating continues

Post by TDJohn »

Have you inspected the exhaust manifold? It is a common issue on these vintage engines to warp and/or crack the exhaust manifold. This causes low boost and the engine to run rich, causing the exhaust gas temperatures to run high which overwhelms the marginal cooling system on our coaches. Also check that you waste gate on the turbo is not stuck partially open, or fully open, this would also cause similar prablem and symptom.

Does the coach seem to have full power?

Does it blow a lot of black smoke?

When the injection pump was installed, was the injection timing set correctly?

I would suggest checking your boost under load, and checking how high you exhaust gas temps run when under full load, like when climbing a long grade.

Please give us as much feedback as possible, regarding your issue and how the engine and cooling system are behaving.

One last thing, consider giving Dave Atherton a call, he is a retired, but still active in the RV community, diesel engine master trouble shooter. He would likely have additional suggestions to what has already been posted. 605-997-0720
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
Safariowner
Posts: 16
Joined: Thu Mar 04, 2021 8:27 am

Re: Overheating continues

Post by Safariowner »

I had a similar problem with my 3126 cat. Ran fine until outside temp exceeded 90°. After several shops and the same things that you did I finally resolved the problem. The radiator fan was put on backwards. It still pushed air out the back but the cupping on fan blades were backwards. Turned it around and couldn't believe the difference in the amount of air being pushed through the radiator. No more problem with heating after that.
Ed and Brenda
1999 4006 Continental
Ex: 1998 3706 Serengeti
Ex: 1993 33' Serengeti
Robert K
Posts: 105
Joined: Mon Oct 28, 2019 2:27 am

Re: Overheating continues

Post by Robert K »

my dash gauge reads 15° higher than the cat reader computer
Bob
96 Serengeti 37'
3126 Cat
6 speed Allison
2011 jeep wrangler towd
Ivory
Posts: 3
Joined: Tue Jun 16, 2020 12:13 pm
Location: Lake Wales Florida

Re: Overheating continues

Post by Ivory »

Waste gate actuator appears stuck. Can't move it up or down by hand.
I will contact Dave to get an expert determination.

Cummins states thermostats don't fully open until 190. They start to open at 170. I verified this in a pan of water on the stove.
Thanks again for all the great input on this issue. Fixing this problem will put the enjoyment back into my Safari.
No more staring at the temp gauge.
Sharongeti
Posts: 5
Joined: Fri Nov 06, 2020 10:44 am

Re: Overheating continues

Post by Sharongeti »

I am having a similar problem. Replaced the top overflow tank, water pump, thermostats new long life coolant and it's still overheating under load. Question. The fan air control switch seems to be disconnected by the previous owner. Why would he do this? Fuel economy? I'm focusing on the fan for now. Any advise would be greatly appreciated.
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