| Oil cooling insight [message #324753] |
Mon, 09 October 2017 13:35  |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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I ran into an interesting observation with engine cooling and the effects of oil temperature. On our Diesel swap I'd by passed the radiator cooling heat exchanger for a couple of reasons. First was because the cooler blocked much of the lower radiator flow which is a real no no with the 6.5 TD. GM went to great lengths to improve H2O flow in 1997 with dual thermostats revised water pump and flow. I didn't want to impair the flow so I crushed the cooler to gain area for H2O. I then added a large air to oil heat exchanger in front of the cooling stack (radiator, charge air cooler). The oil temps seemed to run higher than I liked in hot weather pulling long grates, approaching 250 degrees. I run Rotella full Synthetic so the temps are in line but more than I like.
Anyway, I recently added an additional oil cooler in line with the first cooler. As space is getting to be at a real premium up front, I mounted it in the drivers side wheel well behind the brake prop valve. It has a 12 volt fan behind it thermostatically controlled. I added an oil thermostat after this cooler (I know, a little unconventional).
The results have been nothing short of amazing. I know oil plays a huge part in cooling our engines but didn't expect such a dramatic change.The H2O temps never moved off the stats 195 degree setting and the oil never exceeded 210 (200 degree stat) and the 12 volt fan never came ran on the aux oil cooler. This was with an ambient temperature near 95.
Couldn't be happier with the results and very surprised.
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Oil cooling insight [message #324757 is a reply to message #324753] |
Mon, 09 October 2017 14:39  |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
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Senior Member |
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Hal,
Very interesting. Like Dan would say, if no pictures, it never happened!. Please let us see the installation. I was looking for a high to low air pressure area to mount an oil cooler and didn't want to add heat to the radiator, this might be perfect.
Carey
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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| Re: [GMCnet] Oil cooling insight [message #324762 is a reply to message #324753] |
Mon, 09 October 2017 16:38 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Hal,
Could you please advise:
1) What type of radiator do you have in your Diesel coach; OEM or Aluminum?
2) What was blocked - oil flow or cooling water flow?
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Hal StClair
Sent: Monday, October 9, 2017 1:36 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Oil cooling insight
I ran into an interesting observation with engine cooling and the effects of oil temperature. On our Diesel swap I'd by passed the
radiator cooling heat exchanger for a couple of reasons. First was because the cooler blocked much of the lower radiator flow which
is a real no no with the 6.5 TD. GM went to great lengths to improve H2O flow in 1997 with dual thermostats revised water pump and
flow. I didn't want to impair the flow so I crushed the
cooler to gain area for H2O. I then added a large air to oil heat exchanger in front of the cooling stack (radiator, charge air
cooler). The oil temps seemed to run higher than I liked in hot weather pulling long grates, approaching 250 degrees. I run Rotella
full Synthetic so the temps are in line but more than I like. Anyway, I recently added an additional oil cooler in line with the
first cooler. As space is getting to be at a real premium up front, I mounted it in the drivers side wheel well behind the brake
prop valve. It has a 12 volt fan behind it thermostatically controlled. I added an oil thermostat after this cooler (I know, a
little unconventional).
The results have been nothing short of amazing. I know oil plays a huge part in cooling our engines but didn't expect such a
dramatic change.The H2O temps never moved off the stats 195 degree setting and the oil never exceeded 210 (200 degree stat) and the
12 volt fan never came ran on the aux oil cooler. This was with an ambient temperature near 95.
Couldn't be happier with the results and very surprised.
Hal
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Oil cooling insight [message #324763 is a reply to message #324762] |
Mon, 09 October 2017 18:25 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Rob,
I have one of the Aluminum GMC radiators that had the necks modified-different sizes and locations. I think the lower hose location may have moved it into a more restrictive (water flow) situation as the oil cooler ended up right at the neck opening. At the time there was also a concern with the internal heat exchanger-in my case the lower cooler in the tank, fittings leaking as they were not welded like the upper heat exchanger is. I chose to simply install plugs in the lower cooler and crush it to get more water flow through the lower neck.
I mounted an air to fluid cooler for the trans and also used the in radiator heat exchanger. Trans temps seldom exceed 140F.
Carey, I'll try to get some pictures but it may be a while. I'll have to remove the inner wheel well to document the install.
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Oil cooling insight [message #324784 is a reply to message #324753] |
Tue, 10 October 2017 09:02 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Not good! Oil needs to run at least a few degrees over 212F ASAP when engine is opperating. You are creating a "water farm" in your sump leading to corrosion, and faster oil additive depletion. I'd take 250 over 200 any day especially with T6 Full Synthetic.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Oil cooling insight [message #324789 is a reply to message #324784] |
Tue, 10 October 2017 09:46 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Got to disagree on this one. I've got a 200 degree oil thermostat that keeps oil from the secondary cooler until it reaches that temp. The motor has oil squirters pushing oil on the bottoms of the pistons where the temps are way over pan temp. Boiling out H2O impurities with a turbo charged 20 to 1 compression ratio engine shouldn't be an issue. Whenever boost goes up, piston temps rise dramatically. At 5280' where I live, boiling is at 201 degrees and it's uphill most any direction we travel.
Just my way of looking at it,
Hal
JohnL455 wrote on Tue, 10 October 2017 08:02Not good! Oil needs to run at least a few degrees over 212F ASAP when engine is opperating. You are creating a "water farm" in your sump leading to corrosion, and faster oil additive depletion. I'd take 250 over 200 any day especially with T6 Full Synthetic.
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Oil cooling insight [message #324790 is a reply to message #324753] |
Tue, 10 October 2017 10:10 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Ok given altitude correction you should be ok if you drive it. Idling Diesels use so little fuel/hr on a cold day they may not reach stat temp and sit below it.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Oil cooling insight [message #324807 is a reply to message #324753] |
Wed, 11 October 2017 08:44 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Condenstae is only a problem on very short engine operations. Run it for any length of time and it will purge the water. A queation though - you removed the lower cooler? My coach (stock radiator) uses the lower cooler for the transmission fluid and the upper for oil. The upper is currently not connected, and there's a DeRale forced air cooler for the oil. Which doesn't get it as cool as I'd like.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Oil cooling insight [message #324818 is a reply to message #324807] |
Wed, 11 October 2017 11:11 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Johnny, I used the upper for the trans as the plumbing worked better on my application. The 4L80E trans has the lines on the right and the 6.5 has the engine oil cooler lines on the left. The in tank coolers are on the right hence the routing. The 6.5 uses -10 lines where the oil cooler lines for the GMC were -8 and I didn't want a potential restriction. I used a B&M 29,200 BTU cooler for both transmission and engine oil as well as the 'new' additional engine oil cooler.
I moved the 12 volt fan from in front of the radiator cooler to the new oil cooler in the wheel well. It's controlled by a thermostatic switch located at the forward cooler with a manual override. It hasn't run yet but I'll wait until next summer to know for sure if it's needed.
Fun stuff isn't it?
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Oil cooling insight [message #324824 is a reply to message #324753] |
Wed, 11 October 2017 13:27 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Oh OK. Are thw two coolers the same?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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