Heat not real hot until i rev engine

My truck had no heat. i flused out heater core and opened my resivior lid and squeezed the hoses.. seen some bubbles but i put lid back on and my truck has some heat now.. i rev the motor to around 2500 rpm and it gets hotter. let it back down to an idle and its not so warm. one hose going into heater core is hot but one coming out is just warm

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H H R

Contributor 25 Answers
Posted on Nov 20, 2017

H H R

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Joined: Feb 04, 2016

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I had a 91 GMC 4.3 do the same thing. Liked to froze to ***** one winter. Found I had a air bubble (air lock) in the engine block and heater. It was a bear to get out. Finally installed back flush kit in the heater hose between engine and heater. Took cap off flush kit, pour coolant in through outlet till coolant ran through back to radiator. Replaced cap and started engine. Repeated again. Heater works as good as new. It's using the same principle as priming a gas powered water pump.

5 Related Answers

Anonymous

48 Answers
Posted on Jun 21, 2008

SOURCE: 1996 GMC Suburban Rear Heater Core Hose Removal and Installation

if you can get me a picture i can help you out. blue_dragon45801@yahoo

Rick Davis

97 Answers
Posted on Jan 04, 2009

SOURCE: 95 gmc suburban heater hose

Sorry but its very likely those threads are still stuck in your engine. GM used Plastic, Steel and Cast parts, the most common being a steel that rusts away and gives you the result you now have. You might get lucky removing the broken remains yourself. If you can reach it, you may try an extractor or "easy-out" which is a reverse threaded tool to try and back out the part. however, these are never in an easy to reach location, and more careful extraction may be needed. In that case do not attempt it yourself unless you are very mechanically oriented. you can easily damage your engine block or intake (depending upon where its located). Also note: if the fitting is corroded, so will many other parts in your engine such as the freeze plugs and other fittings. Consider checking these items out as well before big problems arise.

-Good luck

Anonymous

77 Answers
Posted on Jan 08, 2009

SOURCE: 1998 Dodge Durango no heat when using heater.

BLEND DOOR STUCK OR BROKEN. NEEDS TO REMOVE DASH AND HEATER/EVAP CORE BOS TO REPAIR REPLACE.

Anonymous

713 Answers
Posted on Aug 30, 2009

SOURCE: 1999 GMC Suburban heater valve assembly

it is a type of quick disconnect like on the fuel line if you squeeze the taps on the clip the hose should come out pretty easy.

Anonymous

2418 Answers
Posted on Dec 07, 2009

SOURCE: Poor coolant flow through heater core. Heater core

on some GMC models there is a valve that opens when you turn on the heat inside. It is called a heater control / actuator valve, it works off engine vacuum thru hoses connected under the dash, and going to the top of the valve. Now junk and crud and old rust will get in the valve and restrict it's flow. You will have to pull the valve off and clean it, but it is best to replace it, seeing it is hard to get all the junk out of it.
It looks like a L shape pipe with a hose on top & bottom, black plastic,and a smaller line on top mounted close to the wheel well about even with the exhaust manifold on the pass side. Drain the coolant, remove the valve and see if this is the cause, lots of gunk in the one hose. It is not real hard not real easy to replace this valve. Now if your truck does not have this valve check the pipe that the hose hooks to on top of the engine, remove the hose and see if a small screw driver will go down inside or if it is stopped up. .

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