1986 Mazda B2000 suddenly overheating

I've owned this vehicle since Aug 1985 when I purchased it new. It's got 220,000 easy miles on the clock and it still runs great. However, on a recent trip to the Sierras I encountered overheating problems while going up grades to higher elevations. I noticed my temp gauge needle was way up at the top mark and realized that I needed to pull off the highway. The needle actually touched the top mark just so it was hot.

This was the first time this engine has EVER overheated on me. I pulled off and let it cool down (the small coolant reservoir on the right side was spewing coolant like a mini-volcano) but the engine appeared to have suffered no damage so I continued on my way after an hour or so. Subsequently I have experienced several additional overheating episodes with this vehicle and I'm worried about engine damage.

I believe my thermostat is ok since I can run the heater and hot air comes flooding out of the vents like it should. I'm pretty sure that this means that the thermo is working as it should. I also noticed that by running the heat it seems to help the engine cool down a bit. Weird.

I've been told by my mechanic that these Mazda B's suffer from blown head gaskets as they age. So I'm afraid of damaging an engine that is still in fine condition but has LOTS of miles on it. I need to to something but unsure where to start. It's possible the radiator has blockage (original radiator) but I don't know how to check this on my own. There is no leakage anywhere.

When I drive it for 15 min or so it starts to overheat which it's never done before. I'd appreciate any advice before I cry "uncle" and take it back to my mechanic.

sounds like you popped a head gasket run a compression test

to me it sounds like you have two issues. Going up the mountains you probably pushed the engine a bit too hard with an older, less efficient radiator. So my first guess is that your radiator itself is bad and in need of replacing. I recommend looking into getting a dual core radiator for an automatic transmission model 88-93, it will bolt on the same and use the same hoses.

my second guess is in agreement with what Todd said, that you have popped your head gasket. THESE HEADS WARP VERY EASILY when overheated, so you WILL need to take it to a machine shop and have it inspected, straightened, then flattened (IN THAT ORDER). too many overheats will cause coolant to go into the combustion chambers and rust your cylinder walls, making you need a re-ring and hone job as well, so speed is critical.

If your head is cracked then you will need to find a replacement 83-93 B2000 or B2200 will work fine. If you end up getting a good head from a 2.2, you will need to take the plate that the distributor bolts up to from your old 2.0 head and use it on the 2.2 head. And you will want to transfer your mechanical rocker arms over (with rods).

Hey guys - well I got lucky! My mechanic said I saved the motor by pulling over and cooling down whenever it got hot. The problem was my radiator: it was clogged so the coolant could not circulate already. So he had the radiator "rodded-out" for me and put it back in and I'm back on the road with no lasting damage for $309. So mechanical sympathy and alertness saved my rear end. Needless to say I'm very happy and relieved that my trusty B2000 lives on. It's been a fantastic little truck and I plan to keep it as long as I can. So this was a happy ending.

one: welcome to the site
two: glad you got the overheating problem fixed



three: PICTURES

Yes, but something you likely could have done yourself, you'd be happier if you saved $150 and used the mechanic for tougher stuff. Well, at least fixing the existing radiator was environmental. If lucky, mechanic replaced both radiator hoses when he did this job.