I have a 1987 dodge cargo van with slant 6 (bare bones stock) and it is one of most reliable vehicles i ever had.
There is one problem howewer, it runs too cold in the winter.
I have changed the thermostat as i tought that the original one was probably stucked in the open position, but after swaping for a new one, there was no difference.
I made sure that the new one is a "winter" thermostat, so it stays closed the longest before opening (195 degrees i think).
Oh yeah, i tested the old thermostat by throwing it in the boiling water and it is working fine.
So assuming that there was nothing wrong in that department, what else it could be?
I have fastened a big piece of cardboard to the front grill, completely blocking it off.....no result whatsoever.
I'm tired of freezing when i drive as the heater blows only slightly warm air after i been driving it for about 15 minutes.
Anyone can give me any advice as for what to look for?

check to see if coolant is even getting to the heater box. if it is, then the heater box is probably in need of flushing or replacing. if it is not getting coolant, the heater valve (in the hose TO the heater) may be falty. if so, replace it. But then it could be just the cables or vacuum line operating the valve.

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'56 Chrysler New Yorker St. Regis 354
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'71 Dodge Charger Super Bee 383

touch both heater core hoses and see if they feel hot. there should be little difference between them temp wise. if one feels hot and the other cold then you heater core is plugged. also touch the top rad hose. if it isnt hot then you need more cardboard.

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What Your temperature gauge says. Is it getting as hot as summertime. I live here in finland and it's also very cold at this time of year and it usually takes about 15 minutes to at get engine fully warmed.

Is your air cleaner getting heated air when engine is cold?

And block heater is very useful at winter time, you save money and your skin.

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Sorry, my english is not very good

Thanx to everyone for their reply's, i have just purchased a block heater and tonight i'm going to my friends garage to install it and check the heater-core for being plugged or faulty valve.

I have been wondering about this too... I have a 81 D150 only option is power steering! And i was froze stiff last night on the way home! It only has a flat 4 blade fan so i didn't even bother with the winter front ( your cardboard) Can't wait to check the heater hoses when i get home tonight.
Frank

Another vote for a clogged heater core.

Reed

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Casually looking for a Clifford hyperpak intake for cheap.

Yeah thats what i think too... I started the dodge at 1:00 am i checked it at 1:15 and 1:20 about 1:25 i started to think somthing was really wrong i had my hand on the rad after thinking the stant was stuck ( the inlet of the heater core was hot and the outlet was cold) and the rad got hot all of a sudden. (i got dummy lights no real gages) So i think i have to make a trip to the parts store to pick up some coolant before i flush the system. But can i flush the heater core? i mean i'm a good mech but how do i do it other then putting the hose up to the outlet and trying to back flush it with the heater hoses off?
I like driving the slant... belive it or not it is a nice change to a 383 or a 318!
Frank

If you don't want to loose the coolant in the system, take a couple of vise grips, with tape around the jaws, and clamp the heater hoses. Then just disconnect the hoses from the heater core. Now you can flush the core with a hose. Just don't use air pressure, the core will not stand up to more then about 30 psi.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Ok, i'm proud to announce that when i left my friend's shop last night i didn't have to put on my winter jacket, gloves and a fluffy hat with ear-flaps
It was the thermostat, the reason i have eliminated it from the "suspect" list, was the fact that i have changed it last year.
I have tested the heater hoses as someone here suggested and both are nice and hot, so i knew that i had to look elsewhere.
Thanx again for all the tips.

Glad to hear you have heat now

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flushing the heater core worked for me !! I think i could do it some more but my fingers were getting numb! Thanks guys i got HEAT.
Frank
P.S. The slant will warm up in about 8 min on fast idle