heat issue

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#1
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MAKE: Dodge
MODEL:Ram 15004x4
YEAR:1998
MILES:186,000
ENGINE:5.2 v-8
DESCRIBE ISSUE....ok first is temp gauge is barely coming above roughly the 145 to 150 degree mark even though i just put in a new thermostat that is supposed to be a 195 degree one if i crank the blower fan all the way on i get luke warm at best if however i drop it one click its warmer but still not exactly making you want to take your coat off warm i am wondering if possibly the heater core may need to be flushed out?water pump looks to have been replaced not long ago i have only had the truck maybe 6 months also if it sits just idle the air coming out of vents does cool down not sure 100% what is going on
 

billr

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#2
If the engine won't come up to temperature, there is little point to chase other things in the heater system; like core, valve, or blend-door. I can't think of anything that will prevent the engine from heating up properly except the t-stat or some mis-routing of the coolant lines. Even a problem with the coolant line routing is a real stretch, but coolant systems have become more complicated in modern times, so it may be a possibility. The t-stat is what I would look at, even though it is new...

Hmm... I just peeked at Rockauto listings for that t-stat. Some (the cheaper ones) specify "reversed poppet". What do you suppose that means? OP, what one did you put in?
 
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#4
thing is i had this going on before replacing the thermostat all the hoses are proper as i had a mechanic friend do the job for me as i am not fond of working outside in the freezing cold lol
 

billr

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#5
Well, I peeked at that part on the O'Reilly link, it lists 1000 Dodge vehicles it is compatible with and I'm not seeing the '98 Ram 1500 5.2l as being one of them. I'm still wondering why some of them are called "reverse poppet" on the RA site.
 
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#6
it says right on page when i open it fits 1998 dodge ram 1500 and the vehicle i have put in isthe 98 ram 1500 5.2 so it shows it fits other than that i have no idea what the "reverse poppet" means or why they call it that
 
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#7
well upon clicking on more info on rock auto it lists this :
Gates makes several types of thermostats in order to provide the same design as specified by car manufacturers:

- The reverse poppet thermostat opens against the flow of coolant from the water pump. The coolant, under water pump pressure, is used to help the reverse poppet thermostat stay closed when cool to reduce leakage. This type is engineered with a self-cleaning, self-aligning stainless steel valve

- The offset thermostat with jiggle pin valves is equipped with a special valve in the flange, which allows trapped air in the system to escape and permits the venting of air from the system when filling it with coolant
 
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#8
i am also assuming that the temp gauge is registering properly i might take and get the whole system flushed it puts enough out to take the edge off as long as i keep the rpm up it will at least defrost the windshield and its still warmer than not working at all but just not like i feel it should be
 

billr

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#9
Yeah, that link says "98 Dodge 1500 Ram", but it doesn't say which of the (three) engines. Go down that page to the "compatibility" listing. I didn't see your specific config, with 5.2l listed, but may have missed it since there are 1000 in the list.

Understand, I'm not certain that t-stat is wrong, but I know of no other things that will cause the engine to run too cold except a t-stat that won't close properly or piping that has, somehow, been routed to bypass the t-stat. Bad pump/cap/radiator, plugged passages anywhere, air in the system won't do it; all those make an engine run too hot. Have you confirmed engine temp with a separate thermometer? Dash gauges are often not accurate (same for IR guns) and it is vital that we know whether we are chasing an engine heating problem, or a problem with how the heating system uses the engine heat.
 
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#10
i haven't had anything else checked but was told that it could be the heater core partially blocked as to why if i reduce fan speed it gets warmer heat vs with fan on high it only gets lukewarm at best everything else looks to be fine all hoses are run the way they should as top radiator hose runs direct to t-stat i will have to see if i can get the engine temp checked better i don't have but basic tools myself to do most of the basics to my vehicles ie: brakes oil stuff like that i am looking for ideas as to what could be the issue its not over heating for sure just doesn't seem to come upto temp truck runs great other than that
 
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#11
I recommend the "too hot to hold" test. Drive vehicle until gauge is as high as it is going to get. Turn blower fan off. Rev engine 2000 RPM for about 30 secs. At idle, put your bare hand on hose that is engine-to-heater (not heater-to-engine). Try them both is you can't tell the difference. One of them should be too hot to hold for more than a couple seconds. This test bypasses possible problems with inaccurate gauge or partially blocked heater core.
 
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#12
i will try that and see what i figure out i may have to zip to town in a bit so be good chance to do that
 
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#13
ok tried the "too hot to hold" test and surprisingly neither hose was more than warm at best could it be maybe the water pump is going or?? i was expecting one to be blazing hot the other maybe cool but nope
 

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#14
As to the operating temperature, 140* is very hot to the human touch. Can you confirm the actual coolant temperature with a calibrated melt stick, an infrared heat gun, or the like?

Is this an all-original truck, or a made-up one? Somebody on this forum was tinkering with some made-up trucks and I thought they were Dodges. If there's been an engine swap or engine parts swap, funny things can happen. Such as: If an engine was built with accessories driven by vee belts, water pump runs same rotation as crankshaft. Engine built for serpentine belt, water pump is driven off the back side of the serp belt with runs it in opposite rotation. Wrong belt drive, wrong water pump, flow could be wrong and not supply the heater core. In cold weather, the engine might not overheat.

Or simply, is the engine cooling system clogged? Is a heater hose fitting clogged with rust?
 
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#15
So, maybe your gauge is accurate and engine temp is actually low. I know, its a new t-stat so "it can't be that". Next easy test without taking anything apart would be to pinch upper radiator hose so that all heat will stay in the engine.
Drive vehicle until gauge is as high as it is going to get. Turn blower fan to low speed. Pinch off upper radiator hose and let idle while watching temp gauge and feeling heater output. If temp rises to normal range and heater starts to work good, a t-stat problem is indicated. Do not let engine get too hot before un-pinching radiator hose.
Are you sure that cooling system is 100% full? Sometimes the "coolant bottle" has a bathtub ring and fools you into thinking coolant is full when it's not.
 
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