My engine won't heat up enough for the heater to warm up in the cab of the 1998 Ford Ranger 4 cyl. I have been running with cardboard in front of radiator, but not helping much. Replaced thermostat last night, but still only a trace of heat output. Upper radiator hose only gets "comfortably warm" to the hand, and does not build up pressure inside it. Why won't the engine warm up?

60

Asked by Nov 26, 2014 at 01:47 PM about the 1998 Ford Ranger XLT Extended Cab SB

Question type: Maintenance & Repair

New thermostat, new antifreeze, cardboard still in front of radiator, and temperature indicator still doesn't come up!

6 Answers

7,260

Sounds like someone put water instead of coolant in the radiator and now you have rust blocking the heater. Remove the 2 hoses at the Firewall that go the the heater .... now at a very low water pressure ... do not over pressure or you may damage the heater cor ... now try to back flush the heater core ... be careful because when it clears the blockage ... it fly's out like a shotgun blast ... refill with coolant and get a good waterpump anti-rust additive

2 out of 2 people think this is helpful.
60

Thanks, but why (and how) would heater core blockage keep the engine from warming up? The radiator tank and upper radiator hose SHOULD get warm enough that they would be uncomfortable to take hold of with even a 180 degree thermostat, let alone a 192. Why won't the engine warm up and get the coolant hot?

3 out of 3 people think this is helpful.
7,260

Geez ... Usually just the opposite is true ... The engine gets too hot. Read this thread and good luck ~~ http://www.doityourself.com/forum/passenger-cars-suv-service-repairs-no-trucks/410346-engine-wont-warm-up.html I mean ... you have close to 1200 F at the exhaust manifold and yet the engine heat doesn't seem to be transferring to the water. You are contradicting the rules of Thermodynamics ... and of course that's not possible

2 out of 2 people think this is helpful.
10

Did you come to a solution for this problem ? I'm going through the same thing 98 ranger 2.5. New water pump new t stat new antifreeze and just did a head gasket new temp sensors. engine won't warm up any suggestions ?

1 out of 1 people think this is helpful.

have you replaced your thermostat?

25

I am having the exact same issue in my 00 Ranger with a 2.5L. I am starting to think that as the engine block ages with coolant in it that rust is corroding the metal inside and allowing the coolant to get closer than normal to the exterior cylinder walls which is exracting heat too effeciently. Just my theory but I can't think of anything else. I have checked and rechecked everything. I have worked on cars my whole life and never seen anything quite like it. I drove mine earlier today and i drove for 45 minutes without my truck overheating even without a radiator cap and only 1/2 the coolant required. It seems to be an air cooled engine, Ford just never realized it!

2 out of 2 people think this is helpful.

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