Cooling system problem?

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Cooling system problem?

Postby justin.loehlein » Mon Jan 22, 2018 6:45 pm

So, a few months ago I got a low mileage 1990 D250 with a Cummins and auto transmission. I haven't driven it much until recently and I started to notice some odd cooling system behavior.

Under normal driving, the temp gauge sits on the 2nd mark in the normal range, as shown in the picture below.

Image

That's probably fine, but when the truck is coming up to temp, it overshoots that mark by 1/2-3/4 of a section (needle sits straight down or slightly hotter) and then it looks like the coolant starts flowing to the radiator all of a sudden and it gets cold again (almost coming down to the 1st mark) within a few seconds. I noticed it was also spraying coolant out of the overflow tank, though somehow the radiator was staying full.

Great - I figured it was a sticking thermostat, so I pulled it apart to replace it and I found this sitting inside the upper radiator hose...

Image

The PO had a new radiator put in at some point and that was capping the inlet - it wasn't removed before the install, the upper hose was just clamped over it. Anyways, I also pulled the lower and didn't find anything on the radiator outlet or in the lower hose. Threw the new thermostat in and drove it to work today - it's doing the same thing (though it didn't spray any coolant out of the overflow).

I'm wondering a couple things:

1) any thoughts on the coolant getting hotter than normal and then coming down in temp quickly?
2) if there was a cap on the radiator outlet and it got sucked into the motor...how the would you go about looking for it? I'm really nervous that it got sucked into the motor and could possibly be blocking something. I've ordered a water pump and new hoses and am planning on pulling the radiator out and taking care of the KDP anyways, so I can go poking around some more.
1990 D250, auto
1993 W350, 6BT, 5 speed
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Re: Cooling system problem?

Postby Richie O » Tue Jan 23, 2018 12:28 pm

Someone did a great job. :wrench:
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
1992 W250 with NV4500, 3.54's, 16cm 60mm GDS H1C, ground stock cone, Isspro tach, pryo, boost, fuel pressure, slow, rusty, dented,180k
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Re: Cooling system problem?

Postby PToombs » Tue Jan 23, 2018 5:26 pm

Gauge swings are common on these trucks, but not so much if you use a Cummins 'stat. The spray from the overflow may have been caused by the piece you took out restricting flow until it built up pressure.
The lower hose goes on a housing that is removable, so you can check there for a problem. Water makes a 90* turn and goes into the block there. The seal is an o-ring, not a gasket, so you might want to get one before you take it apart.
pete

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Re: Cooling system problem?

Postby thrashingcows » Wed Jan 24, 2018 3:37 pm

Your temperature swing seems normal to me. My truck runs about dead center of the gauge, but when coming up to temps it will run just over the 3rd mark then drop back to center and stay there. Does you gauge keep swinging after it has reached operating temperature? The aftermarket T-stats will just keep swinging up and down, the cummins units don't seem to have that issue.
1984/93 Dodge Crewcab, W350, 1 Ton SRW, long box, 330K Km's, M&H spacer, 366 spring, fuel pin to deep side, 14cm housing, Piston LP, PS IC, Isspro Boost, Pyro and tach, NV4500, 29 spline NP205, 3.54's.


Check out the build....http://www.dieseltruckresource.com/dev/ ... 05923.html
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Re: Cooling system problem?

Postby justin.loehlein » Wed Jan 24, 2018 6:30 pm

Thanks for the info on the swinging gauges. Mine doesn't swing much once it's reached operating temp - maybe 1/4-1/3 of a section in total, dropping when I idle to a stop, raising when I climb a hill, but not much. I drove the truck to work again today and noticed the overflow tank is empty again, though I didn't see any coolant all over the passenger side of the engine bay - maybe I had an air pocket in the coolant. I'll keep monitoring it while I wait for parts to arrive.
1990 D250, auto
1993 W350, 6BT, 5 speed
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fuel screw!!!!
 
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Re: Cooling system problem?

Postby Greenleaf » Thu Feb 01, 2018 9:57 am

the level will drop, after you have refilled and operated the engine long enough to heat and cool.
1990/1992 D250 Ram Diesels Modified by *Smokehouse Diesel* Ashland, Ohio ( )==='==~

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