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Low heat and burning smell Explorer 4.0 V6


New Member
January 4, 2022
Reaction score
City, State
St Louis Missouri
Year, Model & Trim Level
2006 Ford Explorer 4.0 v6
Rubber burning smell coming from engine bay and vents. Heat is minimal and when accelerated the heat returns to “normal” but drops again when you come to a stop.

Background: noticed a burning coolant odor after having transmission replaced. Ignored it for about a month since it wasn’t overheating and got on the mechanics books to repair. The day before I brought it in the radiator cracked. Got the radiator replaced. Then noticed the temp gauge was all over the place and it was overheating. Replaced the thermostat apparently it was cracked in half. That fixed the over heating issue but then it was leaking coolant. Used some stop leak, didn’t do a damn thing. Brought it back for a 3rd time and had the housing replaced as it cracked also. No more leaks but now the heat is minimal unless I accelerate and the is a burning rubber smell coming from the vents/bay. Getting pretty cold here so noticed some sort of belt being squeaky for quite awhile before going away.

My thoughts are a belt/pulley issue for the burning smell and maybe a bubble/clog for heat.

Any advice? Going to a different mechanic or repairing myself as soon as I can spare my daily.

Your thoughts are probably correct with belt or pulley issue for smell and bubble/ clog for heat it could also be a water pump issue. The other possibility is a bad thermostat (my exact problem right now) this will affect the heat because coolant is going to the radiator inested of the heater core. Now I know you said the thermostat and housing has been replaced but is is possible the replacement was faulty.

Do you get any belt squeal on startup or at any other time?

Start up very loud, calms down after engine reaches temp but always there if you listen well enough.

Well then your smell is the belt for sure. Now in order to diagnose anything else you need a new belt at a minimum. You also need to find out why it's slipping is it a belt issue, tensioner issue, or is there a pulley starting to seize up? If it's tension related that could be a possible cause for some of your other issues because the fan and the water pump are driven by the belt and connected together. If your tensioner is original I would recommend it gets replaced with the belt they will lose tension over time.