97 Mazda B2300 2.3L 4cyl won't warm up


  #1  
Old 02-26-19, 12:59 PM
Gunguy45's Avatar
Super Moderator
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 21,112
Received 4 Votes on 4 Posts
97 Mazda B2300 2.3L 4cyl won't warm up

Most of this post was copied from a post back in 2009 by Bluesbreaker. Well, I have almost the same issue, so I'm editing his to fit my truck...lol. Bb, did you ever fix the issue?

I have a '97 Mazda B2300 (Ford Ranger) with 2.3 4 cyl. It's always something with this truck. I guess this is to be expected with a 21 year old vehicle. You may remember I needed the timing belt changed last year but was having problems getting parts off. Well finally took it and the parts to a shop and they fixed me all up for a very reasonable price. Starts and runs great, BUT.....

Now the engine temp won't warm up. Here are the symptoms:

1. Idling or driving around town on a 55 degree day, it barely moved the temp gauge, top hose was warm (not hot...could easily hold it). Same for heater hoses. Heater putting out warm, but not HOT air, where it could roast you before I started the timing belt job last year.

2. Replaced thermostat thinking possibly the new one they installed was faulty. Same problem.

3. Put old thermostat in pan of boiling water and watched it open and then close after taken out of water. Open temp right at 192, fully open at 196

4. After installing thermostat "burped" engine for 25 minutes to purge any air bubbles from system.

5. Drained antifreeze out via siphon into gallon jug before starting stat replacement, seemed a bit dirty. Flushed engine via fill, run for 20, drain (via siphon again) 3-4 times. Remembered I had a can of Prestone engine flush so used that 2nd time. Finally got just "cloudy" coolant. Sun going down so put 90% of previously drained antifreeze back in. Had to go to store (5 miles round trip) still only barely reached bottom of gauge and warm air blowing.

What's the problem here? Yeah, I might need to do a heater core reverse flush (anyone know what appears to be some sort of bypass/mixing valve in heater circuit is?), but engine not heating? Everything says stat stuck open or faulty gauge...but I believe the gauge, since the hoses never get hot and heat is lukewarm.

Man, I do not want to take this back to the/a shop! It's got to be something relatively simple. I highly doubt the shop did anything wrong, they're very experienced and highly rated. So , what could have happened while it sat for so long to cause this now? All engine openings were plugged, no mice or anything. Radiator was taped up and stored in the garage. New main hoses. If it was OVERheating...I'd think blockage or corrosion or something...but it's the opposite.

Next up is long severe duty flush and back wash of radiator and heater. What else to try?
 
  #2  
Old 02-27-19, 02:18 AM
A
Member
Join Date: Aug 2015
Location: USA
Posts: 653
Received 26 Votes on 25 Posts
seems like it would be a thermostat based on the symptoms low temp gauge and warm air, think I would probably try a new one, looks like it has a vacuum operated heater control valve some vehicles do use these so they do not circulate coolant through the heater core unless you are using the heater could check and see if the vacuum diaphragm is working on it.
 
  #3  
Old 02-27-19, 05:15 AM
D
Forum Topic Moderator
Join Date: Sep 2012
Location: USA
Posts: 1,141
Received 58 Votes on 49 Posts
One thing you need to keep in mind, speaking of the gauge. The gauge monitors the block, not the radiator, so, even if the hoses are "warm", if the water isn't circulating, your engine may be hotter.
Lets say a hose is collapsing, or the thermostat isn't opening... or opening yet... that would keep the water in the radiator... it may not be circulating. So having said that, just because the hoses are warm, doesn't mean the engine isn't hot & you have a bad gauge.

All I am saying is keep this in mind. I am not saying this is your solution because you have done everything I would have done & like you, I am at the end of my knowledge on this subject. I'm just trying to think about ANYTHING, that might give you or another member, a brain storm here.

Good luck....
 
  #4  
Old 02-27-19, 12:15 PM
Gunguy45's Avatar
Super Moderator
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 21,112
Received 4 Votes on 4 Posts
Thanks....
About the heater core and what that snakes nest of hoses is, I believe you are right, Alan. The temp control knob is VERY easy to turn, so no cables...has to be vacuum operated. And there is some sort of "ball" with vac hoses and short cables coming out of it...likely thats the "controller".

I would agree with the stat....but this would be the third one! The original worked, the brand new one they put in apparently didn't (and it functions fine in a pan on the stove), and now the one I put in isn't. The first 2 are marked "Motorad" so the same brand. Last one, not sure.

Did find one thing in Ford forum where a guy had leak through on his stat (none are completely watertight anyway) due to the horizontal orientation and design of the housing...it just doesn't seal well internally. So there is some water leaking by no matter what. Since the rad is relatively large for the engine size as well as having an 8 blade fan and shroud...apparently any leak by is bad. Because the hoses and rad water do get warm (I can put my finger in the coolant and hold the hoses) but not hot...there has to be SOME flow.

One guy said he actually took his fan OFF in winter months and had zero issues. Another blocked 2/3 of his rad to get heat in winter. The last guy I mentioned above actually added a o-ring to the internal sealing surface of the housing, which apparently did the job for him.

It's really a PP design, when you can't keep the stat well positioned in the housing as you are trying to maneuver it back into position blind and put the bolts in. I tied a thin cotton string to the stat to keep tension on it during install...that certainly helped, but who knows if it stayed there? Even my Suzuki has the stat permanently installed in the housing, so never an issue with movement. Oh for the simple days of '67 Pontiacs and small block Chevys. Change a thermostat in less time than it took to get the tools, w/o even taking the hose off.

Going to try the o-ring likely tomorrow after I get ANOTHER new gasket and the right size o-ring.
 
  #5  
Old 03-04-19, 05:48 PM
Gunguy45's Avatar
Super Moderator
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 21,112
Received 4 Votes on 4 Posts
Well, the O-ring, a liberal amount of black RTV on both the O-ring and the rubber stat seal, along with careful positioning of the stat and a couple of homemade studs to make it easier to align and I have an engine that comes to operating temp and will singe the hairs on your arm with almost 155° heat. (Just in time for summer! Yay!)

Just plain ole PP design of either the housing or the stats...not sure which.

A few bubbles to work out (gauge varies slightly depending on engine speed), but time will take care of that.

Also modified the shroud that you couldn't remove completely unless you first removed the fan and clutch or the fan and rad. 5 min with an oscillating saw and now I just have to remove the fan. Think I may look at it again and just cut the shroud in two to make future work easier.

Like the truck, hate the engineering.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: