Kalal92 Posted March 14, 2016 Share Posted March 14, 2016 Engine doesn't seem to be cooling down much while running boiling in overflow but not overheating Link to comment Share on other sites More sharing options...
fiatslug87 Posted March 15, 2016 Share Posted March 15, 2016 I believe the stock thermostat is 195° for a 4.0L, not sure about others. What year is your truck and what engine? Link to comment Share on other sites More sharing options...
yxmj Posted March 15, 2016 Share Posted March 15, 2016 Take the stat out and test run it...if it runs cooler it is the t-stat......if it maintains the water level but still bubbles up in the over flow.....it is your water pump....if it is losing water without any noticeable drips or damp spots...it is your head gasket . :MJ 1: . Link to comment Share on other sites More sharing options...
Kalal92 Posted March 15, 2016 Author Share Posted March 15, 2016 86 4C 2.5 Link to comment Share on other sites More sharing options...
jdritch Posted March 15, 2016 Share Posted March 15, 2016 According to ALLDATA: . On all engines the thermostat is closed below 195°F (90°C) . This is on the 4.0L motor. Your water pump could be starting to go out. A way to test a thermostat that i have seen is to take it out and put it in really hot water and watch to see if it opens. You can test the water pump by: With the engine off and the key removed from the ignition, attempt to move the pulley from side to side and back and forth. There should be no detectable movement. The pulley should turn smoothly, with no rough spots. The water pump should be replaced if any pulley wobble is detected. If the water pump is not replaced the pump shaft may eventually seize or break. OR After the engine has warmed carefully feel the upper and lower radiator hose. The temperature of the hoses should be very close or the same temperature. If the top radiator hose is hot and the bottom one is cold then it could be your water pump because that would mean that the coolant is not circulating.(how we tested the mustang) My dad has a mustang and it would keep overheating and we tried 2 new thermostats and finally we checked the water pump and found out its bearings were going bad and on the inside the blades of the water pump had ground a deep groove into the water pump housing. The coolant also had a rust color to it. The water pump was not creating enough pressure. Link to comment Share on other sites More sharing options...
Kalal92 Posted March 15, 2016 Author Share Posted March 15, 2016 Recently replaced water pump and thermostat. Link to comment Share on other sites More sharing options...
Eagle Posted March 15, 2016 Share Posted March 15, 2016 Recently replaced water pump and thermostat. You may just need a new radiator pressure cap. The 2.5L has a conventional overflow catch bottle, not a pressurized surge tank like the Renix 4.0Ls. The coolant doesn't circulate through the catch bottle, and once coolant gets to the bottle no heat is added (except if more coolant enters). That means it can't boil in the catch bottle -- but if the temperature is above boiling (212 F) when it hits the catch bottle, it will boil because it's suddenly going from pressurized (at whatever your pressure cap is rated for) to atmospheric pressure. I believe the factory cap is rated to 13 psi, and that raises the boiling point from 212 degrees to somewhere around 240 or 245 degrees. If the pressure cap isn't doing its job, the coolant in the system will boil at a lower temperature, which will cause more of it to expand and to flow out into the catch bottle. Link to comment Share on other sites More sharing options...
75sv1 Posted March 15, 2016 Share Posted March 15, 2016 What Eagle said. Try and replace your pressure cap or radiator cap every 5 years. I had this on a 78 AMC Gremlin. Lost coolant. Replaced the thermostat. Nothing. Then read 'Automotive Repairs for Dummies' by Denna Sclar. Replaced the thermostat, coolant kept at the required level. Link to comment Share on other sites More sharing options...
Kalal92 Posted March 19, 2016 Author Share Posted March 19, 2016 Changed radiator, water pump, thermostat, cap, hoses still not cooling down and blowing cold air when heat is on high. Is there a possibility that the new water pump could be bad? Link to comment Share on other sites More sharing options...
yxmj Posted March 19, 2016 Share Posted March 19, 2016 Just a question....your sure it is the right pump? there are pumps that turn the other way... :dunno: Link to comment Share on other sites More sharing options...
Kalal92 Posted March 20, 2016 Author Share Posted March 20, 2016 The one I replaced had a broken rotating piece Link to comment Share on other sites More sharing options...
Eagle Posted March 20, 2016 Share Posted March 20, 2016 Just a question....your sure it is the right pump? there are pumps that turn the other way... :dunno: Corect. Especially wiuth an '86 2.5L this is a very real possibility. If you have conventional vee belts, you need a straight or direct drive water pump. If you have a serpentine belt, you need a reverse rotation water pump. They look alike on the outside and they both bolt up to the engine. Link to comment Share on other sites More sharing options...
Kalal92 Posted March 20, 2016 Author Share Posted March 20, 2016 I have a vee belt ( pretty sure Link to comment Share on other sites More sharing options...
Kalal92 Posted March 20, 2016 Author Share Posted March 20, 2016 Looks right. So jeeps from 80-86 had v belts Link to comment Share on other sites More sharing options...
yxmj Posted March 20, 2016 Share Posted March 20, 2016 Easy test without pulling off the pump....take off the T stat housing and pull the stat...put the housing back on with no stat....remove the Other end of the heater hose we can see in your picture above and stick it in an empty milk jug...have a helper turn the motor over...if the water pump is spinning the right way it will pump water into the jug.... If you try this be careful :dunno: Link to comment Share on other sites More sharing options...
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