I have a 2.5 98 ranger. This past weekend I put a t-stat in it because it was sticking open and I could not keep the engine at operating temp, becasue of this I had no heat as well. After the replacement I am still having some trouble. Now I have heat as long as I am moving Once I come to a stop the heat is no longer working. I am thinking I may have a bad water pump but unsure. What do you think?
what exactly do you mean by having and not having heat?
My old 'yota pickup had a blown HVAC fan, but at speed there was enough air movement to push hot air through the vents.
Do you mean something similar, or do you mean that when you slow down, the air keeps coming, but starts blowing cold?
heat in cab or heat on gage?
Do you have any air bubbles in the coolant system? Jack up front end, pull rad cap and run until you see coolant flow (t-sat opened). That should burp out the air.
what does the temp needle do?
The HVAC fan is working not the greatest but it works good. When I have heat the temp gauge is slightly elevated but not much. The gauge will never read that I am at operating temp unless I am really getting on it pretty good. When I lose the heat the temp gauge is all the way passed cold like its off. I am not sure about an air bubble, I could give that a shot, any other suggestions?
That's weird.
I am stuck,and I am not in a position right not to throw parts at it until I fix it, but who ever really is.
But a new thermostat and it won't build heat. I don't even know what to try if you did have money to throw around.
I think that it may be a water pump, but I would think it should over heat.
jrao83 wrote: I think that it may be a water pump, but I would think it should over heat.
I agree... if the water pump was shot it's not going to cause it to overcool.
What about the termperature sending unit? Do we know for a fact that it's not building heat, or is this all based upon the reading of the temp guage?
I'd agree if not for the lack of heat out the vents.
belteshazzar wrote: I'd agree if not for the lack of heat out the vents.
Sorry, my ADD is kicking - I thought I was the only one that had mentioned anything about heat not coming out of vents, and that was with my old 'yota.
Did the OG poster say that, too?
lol. you're allowed to scroll up and look.
Heh, that was my polite way of saying I don't believe the origingal poster ever said anything about heat coming out of the vents. 
yeah I have heat coming out of the vents, but only when I am moving.
would the temp sending unit cut off my heat somehow if it was reading incorrectly???
Sounds like a classic resistor problem on the blower. Are the vents controlled by vacumn ? Could be a problem there.
What if you are not moving and hold the engine at 3,000 RPMs, do you get heat then?
Just trying to figure out if it is a moving truck or a faster spinning engine that makes the heat work.
ignorant's right, classic symptoms of an air bubble in the cooling system. If you look closely, you will see that the top of the heater core is above the top of the engine, meaning an air bubble gets trapped there. Those things are a beeyotch to 'burp', sometimes you have to take the radiator cap and upper heater hose off, hold the end of the hose up above the level of the heater core and the top of the radiator, fill the cooling system and heater core and hoses through the hose until coolant comes out of the radiator cap opening and the upper heater core fitting then stick the hose back on quick. It's messy but it works. It's easiest if you use a kitchen measuring cup or similar.
Jensenman wrote: ignorant's right, classic symptoms of an air bubble in the cooling system. If you look closely, you will see that the top of the heater core is above the top of the engine, meaning an air bubble gets trapped there. Those things are a beeyotch to 'burp', sometimes you have to take the radiator cap and upper heater hose off, hold the end of the hose up above the level of the heater core and the top of the radiator, fill the cooling system and heater core and hoses through the hose until coolant comes out of the radiator cap opening and the upper heater core fitting then stick the hose back on quick. It's messy but it works. It's easiest if you use a kitchen measuring cup or similar.
This will work, I do the jack up the front end deal cause I am lazy. The key is to get the rad cap/filler neck to be the highest point in the system.
I think the vents are controlled by vacuum via a little box behind the glove box.
Maybe get a higher temp thermostat and/or block off airflow to a portion of the radiator.
If it is an air bubble trapped in the heater core than why does the temp gage drop down so low? Isn't the temp sensor near the back of the block on the driver's side and measuring actual temp of coolant in the engine? Is this two problems?
Any time the temp sender bulb is not in contact with hot coolant the temp reading can drop even if the engine is hot. BTDT. For that matter, if there is an air pocket trapped behind the thermostat it's probably not going to open because there's not enough heat being transferred to the wax 'motor' that pushes it open.
So, temp runs a little high at idle = coolant is low, causing mild overheating, gauge fluctuations also could be due to an air pocket trapped there. There's coolant in the heater core = heat from vents.
Take off down the road, the water pump speeds up and basically sucks the coolant out of the heater core and back into the engine. This is because in most cases the heater core is on a 'bypass' part of the cooling system, not on a main coolant path like a radiator hose. No coolant in heater core = no heat. That coolant is now in the engine and the mild overheating diminishes or the air pocket gets pulled toward the water pump = temp gauge goes down.
Slow down, now some coolant gets back into the heater core, cycle starts over.
I have seen some thermostats which did not have the jiggle pin or air bleed hole making it really a beeyotch to burp an air bubble from the cooling system. That can also happen if the jiggle pin/bleed hole is installed pointing down rather than up, easy to do on some cars.
Can't the stats on a Ranger be put in backwards? I thought there was something screwy about this truck, with regards to the stat.
TJ wrote: What if you are not moving and hold the engine at 3,000 RPMs, do you get heat then? Just trying to figure out if it is a moving truck or a faster spinning engine that makes the heat work.
yes the faster the engine is spinning the more heat I have. The temp gauge will also work under increased rpms
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