99 XLT blowing cold

[Rainmaker]

My Ranger's heat doesn't seem to be functioning ideally and given that it's been a high of 0 degrees many of the last several days this is certainly a problem. Once the truck warms up I can get some heat out of it in the lower 2 fan speeds but any higher and it's just blowing ambient air. No indications it's the head gasket, I changed the oil last weekend and no evidence of coolant mixing there or in the reservoir. This is also the first winter I've driven this car so this may have been going on for a while before I owned it. Any ideas would be greatly appreciated.

 

[RonD]

The Lima engine is cold blooded, lots of metal to keep warm in cold weather.
Many use radiator cover(cardboard) to limit cold air from coming into engine bay when driving, this helps.

Is the dash board temp gauge running cooler than it did in warmer weather?
If so then engine is not heating up.

If not then heater core could be getting plugged up, less flow means less available heat so core cools off fairly fast when fan is on.
After engine is warmed up, pop the hood and feel the 2 heater hoses one will be warmer than the other, warmer one is the IN from engine, cooler one is the OUT of core.
Turn fan to high, if IN is alot warmer than OUT then core is most likely clogged, if IN is just luke warm then engine is running to cold, block rad air flow.

You can Back Flush the heater core if it seems clogged.

Lima engine should be running a 190degF thermostat(192, 195 or even 205 are available), that means radiator should not get warm until coolant temp in engine reaches 190degF.
And even then thermostat won't be open fully until coolant is at 205degF.
Start engine cold, feel upper rad hose, it will of course be cold.
Wait 2 or 3 minutes, feel upper hose again, should still be cold, if it is warming up with the engine then thermostat is not closed and will need to be replaced to get heat back up.
At 0degF it should take 5 to 8mintes for engine to heat up coolant to 190degF, and upper hose would start to get warm then

Radiator is there for extra heat dissipation, and in cold weather it may not be used at all, that is why the thermostat is there, it keeps engine warm in cold weather

 

[tomw]

Only thing I would add to RonD's words is that both heater hoses should be too hot to leave your hands on them when the engine is up to normal temperature.
If you decide to replace your thermostat, use a good brand, such as Stant, Motorcraft or RoberShaw. The el-cheapo ones likely will not work as well, nor last as long as a good stat.
I think 195F is the Lima choice, but check a parts manual to be sure.
tom

 

[Rainmaker]

Thanks guys. I went through the routine and I didn't find anything convincingly conclusive. Dash gauge functions normally, rad hose doesn't seem to heat extraordinarily fast. I did feel a difference on the heater hoses initially but they seemed to even out after a while. They never did get so hot that I couldn't hold my hands on them (felt pretty nice at 7 degrees outside...). For now I'm going to heed my old man's advice and replace the thermostat first and see where that gets me. If you happen to know a safe way to blow out the core that doesn't involve hose water (seems like a bad idea at this temperature) I'm all ears.

Thanks again!

 

[RonD]

Drain some coolant out of rad, low enough so coolant won't come out of heater hoses when disconnected.
Remove heater hoses but at Bypass/heat control end not firewall end.
Put IN hose in a bucket/container, and blow into OUT hose, see what comes out.
Heat up some water and mix in CLR or Vinegar, pour it into heater core OUT hose.
Let it sit for 20 min then blow it out, using OUT hose again and see if more debris comes out IN hose.
Repeat as you see fit.

You don't need air compressor, lungs will be fine, longer heater hose(s) might make it easier and it isn't expensive by the foot.

Heater core has the same size IN/OUT openings, so there should be no resistance to speak of when blowing thru it, so you should be able to tell if it is plugged and if the hot water and CLR is working to open it back up.

 

[Rainmaker]

Well that all seems simple enough, I'd read that using compressed air could cause some damage but this seems like a safe alternative. Thanks again!

 

[RonD]

Well that all seems simple enough, I'd read that using compressed air could cause some damage but this seems like a safe alternative. Thanks again!

Yes, you could use stupidly high pressure on a CLOGGED heater core and cause solder joint to fail, or blow out a weak corroded piece of a tube.

But common sense would prevent 99% of people from doing that, yes I am optimistic about common sense

Compressed air is fine to use, just dial it down, cooling system runs with 14-18psi(rad cap rating) when warmed up, people commonly test for leaks with 20-25psi pressure in system so just dial it down and you will be fine.

Your lungs can generate about 2.5psi so blow as hard as you want

 

[CajunPwnStar]

I removed both lines, took a garden hose and kinked it, held a good fit on the inlet to the heater core, and let the garden hose go and kind of pulsed it. You don't want too much pressure going in. A ton of gunk came out and I decided to do a full system flush and replace the thermostat. When I pulled the thermostat housing off, this is what I found....

No telling when that little '95 had it's coolant system looked at

 

[jeremysdad]

Your pictures are gigantic. lol

OP, any progress?