my 99 was weak also. i found if i set mine to recirc. it had a bit better heat.

 

Right now, I have a Mopar 195 with a jiggle valve, I was getting the same with the 205 however. Checked everything with an IR gun and found the thermotat housing was at 205 ish (when the 205 was in the jeep).

so with the 195 in the jeep, I checked the heater inlet with the gun last night and was getting 175 at the hose to the heater core inlet.

am I imagining all of this really? is the normal temp in the cab supposed to be 130-135"

 

Is the air intake clear? Check under the cowl.

 

Ok, I think I would go back to the temperature then and sort that out first. I have a diesel vehicle and when it runs cool, it doesn't throw heat for a darn!

Water pump:I've seen water pumps work when it's cold, but when it heats up the expansion caused the impeller to loosen and slip. Or could be another issue

T-Stat. Could be lightening struck twice. I'd throw another one in.

Lower Radiator Hose: Ensure it's firm, not sucking in as you rev and preventing water flow.

Hoses: Might be worth checking something hasn't come apart and reducing flow when things heat up.

 

Also pull the fan and make sure you still have fins. Look in there for varmint nests.

Did you ever replace the blower motor? Some aftermarket manufacturers have the wires reversed.

 

Delete.

 

never changed the blower motor because I have flow through the core and I drive it daily so the likelyhood of animals getting in there are slim.. What are your typical temps that you get?

 

I'll go check but take a look under the cowl. This sounds more like an airflow problem. If both radiator hoses are hot then the fluid flow HAS to be OK.

 

My '01 would get hot enough to melt the rubber off ones shoes.

 

I got 122 degrees with 27 degrees ambient.

 

bush mechanic test, remove any valves, disconnect & seal relevant vacuum valves, set doors manually if possible

now heater core is always getting hot water, and you should be getting heat

over here, some people seal the heater off with taps,(on other vehicles mainly) as they are only ever needed at night, in winter

on a jeep, the heater core with max fan can be used if ur overheating..like an extra radiator... lovely experience to be inside!

weather is fantastic here atm, but not far away, there is an incredible heatwave, with temps forecast 43-49C today (110-120F)

 

 

Thanks for this Dave, now I have a "perfect" baseline to judge temps.