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rein
Regular
Date registered: Sep 2006
Location: Ontario, Canada
Vehicle(s): '83 SWB 280 converted to TD, "86 sold
Posts: 71
| Diesel conversion overheating
Hi all. Could use some help in solving what appears to be an overheating problem on my conversion (from day 1 actually). 1983 280GE to 617. Turbo diesel. Dash gauge hooked up to sensor on block. Recored rad, new water pump, and thermostat. |
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AirheadNut
Member
Date registered: Nov 2016
Location: Montana
Vehicle(s): 1988 280GE SWB
Posts: 31
| RE: Diesel conversion overheating
I have had similar problems with mine: it would try to overheat after a long stint at highway speed. I discovered that there is no radiator overflow reservoir on my conversion, so any expansion of the coolant would force some out the overflow hose onto the ground. Over time enough coolant would be lost that heat soak would set in during extended periods of high load. |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Diesel conversion overheating
When it is running hot: 1) is the radiator hot (use an IR thermometer or IR camera)? If not there is a flow problem.
2) if it is hot, do you hear the fan roaring? If not, the fan clutch is shot
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| Re: Diesel conversion overheating
My personal opinion, based on own experience is that 280 GE radiator is simply not capable of cooling diesel engines. On one of my early conversions I tried what not with not great success , until I replaced the radiator with aftermarket one. At which point the problem was solved. |
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rein
Regular
Date registered: Sep 2006
Location: Ontario, Canada
Vehicle(s): '83 SWB 280 converted to TD, "86 sold
Posts: 71
| Re: Diesel conversion overheating
Thanks for the ideas so far. I will put them to the test. Titus, what rad did you use? Could the diesel temp sending unit be incompatable with the gauge for the gas engine? |
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rein
Regular
Date registered: Sep 2006
Location: Ontario, Canada
Vehicle(s): '83 SWB 280 converted to TD, "86 sold
Posts: 71
| Re: Diesel conversion overheating
Hi again, what is the difference between a diesel rad and a gasoline rad? |
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Warren T
Extreme Veteran
Date registered: May 2006
Location: Montreal
Vehicle(s): 230GE,300GD,300D
Posts: 519
| Re: Diesel conversion overheating
There,s no reason a radiator designed to cool a 2.8 litter gas engine can,t cool a 3 litter Diesel.
Of course the Rad must be in good shape and not partially blocked.
I have installed 18 617a engines in gas G,s always reusing the original Rad and the few that ran hot were cured
by recoring the Rad.
These engines are 30 plus years old, so before installing i would recomend removing the aluminum water pomp housing
on the front of the motor to expose the bottom of the water jacket. I have seen the port to the pump half closed
by accumulated crud. This is a good time to check clearence between water pomp impeller and the housing.
The housing may have been damaged at some time by bad pump bearings and some aftermarket pomps
had the impeller too far from the housing that reduced pumping efficiency.
My personal 460 with a 617a and automatic is running the 280 Rad with no fan onthe engine and no oil cooler.
Only in very few instances will the temperature rise (steep inclines at low speed or heat soak at iddle after a high speed
hyway run. I have a manually activated electric fan that brings everything back to normal.
Rein...the sending units are the same for gas or diesel (will be market 120c) This is the temp at which the sender
is completely grounded and guage is at it,s limit in the red zone.
Weak grounds in a 460 will cause the temp. and gas guages to overead. Use a infrared thermometer to veryfy the guage accuracy.
Warren |
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rein
Regular
Date registered: Sep 2006
Location: Ontario, Canada
Vehicle(s): '83 SWB 280 converted to TD, "86 sold
Posts: 71
| Re: Diesel conversion overheating
Hi, anyone have a good oem oil cooler For a 280GE? |
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emlmcb
Veteran
Date registered: Dec 2006
Location: Buenos Aires, Argentina
Vehicle(s): 1986 LWB 300GD / 1998 E320 / 1996 LWB G300TD
Posts: 119
| RE: Diesel conversion overheating
I fully agree with Warren.
There is no reason why the 280 radiator could not be enough for a 617.
Down here there are several 617 convertions still using the original 230 radiator.
Every time I had an overheating problem, it was either wáter pump, radiator or thermostat, all of these provided that your instruments are well gounded, either they will show higher values than the real ones.
There are some simple testsl to do to sort out the source of trouble:
a) Look at your temp gauge needle and turn on the lights: If the needle jumps to a higher value, you have a ground wire problem.
b) Let the engine idle for some time. If there is overheating in this contition, accelerate the engine (trans in neutral) and look if temp goes down. If it does, it is most likely that the wáter pump is not flowing enough wáter al low revs.
c) Remove the lower hose of your radiator, cover the outlet with your hand and have someone fill the radiator with wáter. Remove your hand and wáter should flow freely, filling the whole diámetre of the pipe. If it does not, the radiator is restricted.
d) If neither one of the former happens, take a look at your thermostat. It may be stuck partially closed or at your fan clutch.
Hope some of this helps |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Diesel conversion overheating
emlmcb - 11/24/2016 10:34 AM
I fully agree with Warren.
There is no reason why the 280 radiator could not be enough for a 617.
Down here there are several 617 convertions still using the original 230 radiator.
Every time I had an overheating problem, it was either wáter pump, radiator or thermostat, all of these provided that your instruments are well gounded, either they will show higher values than the real ones.
There are some simple testsl to do to sort out the source of trouble:
a) Look at your temp gauge needle and turn on the lights: If the needle jumps to a higher value, you have a ground wire problem.
b) Let the engine idle for some time. If there is overheating in this contition, accelerate the engine (trans in neutral) and look if temp goes down. If it does, it is most likely that the wáter pump is not flowing enough wáter al low revs.
c) Remove the lower hose of your radiator, cover the outlet with your hand and have someone fill the radiator with wáter. Remove your hand and wáter should flow freely, filling the whole diámetre of the pipe. If it does not, the radiator is restricted.
d) If neither one of the former happens, take a look at your thermostat. It may be stuck partially closed or at your fan clutch.
Hope some of this helps
Excellent trouble shooting guide. Thank you! |
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rein
Regular
Date registered: Sep 2006
Location: Ontario, Canada
Vehicle(s): '83 SWB 280 converted to TD, "86 sold
Posts: 71
| RE: Diesel conversion overheating
Good day. The needle does jump when there is a current draw. I will look into that. The rad has been re-cored and the WP replaced. I will also take a good look at the fan clutch (I do have an electric auxiliary, but engaging it might exacerbate the possible ground issue). Thank you all for your assistance thus far. I will keep you posted. |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Diesel conversion overheating
It is a basic troubleshooting tenet: If all the measurements look wrong, verify the measurements first.
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Warren T
Extreme Veteran
Date registered: May 2006
Location: Montreal
Vehicle(s): 230GE,300GD,300D
Posts: 519
| Re: Diesel conversion overheating
Nice to hear from you Edwardo....good diagnostic method which reminds me...in the cars these motors were helped
by an electric recirculating pump in the heater circuit. None of this in the G. The trick is to use a water pump pulley
from a 1985 300SD (126 body) The pulley has a smaller diameter so water pump and fan turn faster at all speeds.
It was only used on 1985SD and uses shorter belts (1005 vs 1035)
Warren |
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emlmcb
Veteran
Date registered: Dec 2006
Location: Buenos Aires, Argentina
Vehicle(s): 1986 LWB 300GD / 1998 E320 / 1996 LWB G300TD
Posts: 119
| RE: Diesel conversion overheating
As always, you are right, Warren.
You may remember from the time you visited us, that in my former G (the 460) I had added an inline electric wáter pump. I did not keep it running all the time, just on extreme conditions like heavy sand or steep climbs in very hot weather.
It did a lot more to keep temp down tan keeping the electric fans on.
Fortunately, in the 463 I never had any temp. issues.
Regarding the ground wire issue, adding electric equipment will not make the problem worse if the instrument panel is properly grounded.
The temp. sending unit is nothing but a variable resistor and the temp meter is actually a volt meter.
When temperature changes the resistence of the sender, there is a different voltaje drop in it and thus the meter shows a different reading.
Believe it or not, when the instrument panel is not properly grounded, the small current drawn by the instruments lights produces a voltaje drop that distorts the reading.
Cheers
Ed |
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