Just a little word of caution.

Running no thermostat might be a bad idea. Firstly it will take a lot longer to warm up your engine. This could reflect in MPG going down as it runs it on enrichment for much longer than needed.

Then there is the issue of upsetting the flow of coolant. No thermostat can actually fry an engine (not sure on our V6's) but from the top of my head no thermostat would open a bypass for the coolant to run from pump to radiator. Water (hydraulics) will take the path of least resistance and you may end up with the back portions of the block and head not getting enough flow to properly cool.

Just my 5 cents worth of thoughts.

 

I can actually say a jammed up thermostat can kill a small block
My truck is on its second motor due to that actually, the previous owner never replaced it and when it was about 16 years old the radiator side tank blew out partially from a bad blowoff cap and partially from the backpressure from the jammed shut thermostat, overheated on a dark bridge and spun 4 bearings.

 

I know the warm up and enrichment could be affected, I'm curious if it matters that much since it's 80F+ here most of the time. Very interesting comment about the flow, I certainly hadn't thought about that. I would think they wouldn't dyno engines with no t-stat if it was that big of an issue, but I am no expert. And I always appreciated your 5 cents @error_401 I doubt there are many who are more familiar with 4.3's than you.

I really just need to get a new rad, or have my professionally cleaned out as it's definitely a little blocked up. So was just thinking no t-stat might help a little for the time being. I may not take it out, we'll see. It was just a wild idea anyway, since it's free, and easily to put back.

 

Yea, stuck closed is a big problem. . .sorry to hear. I've never seen it happen on anything American, but that happened with my Audi once (with a brand new t-stat) and had to get the head fully rebuilt and machined.

Cooling system always seems to be one of the most neglected areas on older cars.

 

Thanks,

Yea - stuck closed can kill an engine especially in high outside temperatures. Thermostats have sometimes been removed in racing engines but AFAIK and talks to the mechanics they had either just removed the valve part of a thermostat (the small spring loaded tab) or used a restrictor plate. It will depend on the bypass plumbing to ensure correct flow. To get me home with a thermostat stuck closed, I would eventually, if no other solution is possible, remove the thermostat and drive it at lowest possible load with the heating at full. Could hopefully take you home without damage.

With these modifications we should always acknowledge the data that is available to us. The temperature sensors may or may not be located in the worst possible location for heating. Some people address this discussion by simply pointing out that their temp gauge showed it to be cool. But without proper sensors mounted all over the cylinder head and block we can't really tell. IMHO an expensive R&D project.

The guy at my machine shop has successfully tested and since deployed a lot of modifications especially to very old engines (pre-war) but also more modern modifications. Coolant flow to all cylinders, especially to the exhaust part of the cylinder heads is important. In some engines to overcome heat related issues (burning up head gaskets) they found that some manufacturers had way too big passages and measuring the water pressure delivered by the water-pump showed that the farthest away cylinders had not even half the pressure (hence half the coolant flow) than the front ones.

On the Blazer's V6 we have the heating element which taps into the heads directly at the aft cylinders. I'm planning on fitting a switching valve in order to bypass the heater core for summer. But the solution will definitively be a "bypass" to keep the circulation.

 

As always a wealth of knowledge. . .I guess I won't bother with removing it, and will focus on the other things.

As far as the by-pass I actually have a vacuum actuated bypass valve to do that sitting around, so maybe I should worry about that instead.

 

Just got my Electric Fans installed. . . at least most of the way. Have a little bit of finishing work to go along with it, but I already have a some thoughts in regard to the conversion.

1. The Fan Wiring/Relay Kits I used came with temp switches that activate at 200 degrees, and shut off at 185. While it didn't overheat while it idled during testing, I don't like how late the fans kick on from the temp switch. Should just be a simple matter of buying another temp switch with a colder range. Looks like I'm going to order one that turns on at 185, and off at 170. . .which will work best with my 180 degree thermostat. On a positive note, the temp switch was the easiest part of the job since there was an unused 1/2" npt plug on top of the water pump.

2. I need to add some kind of Trinary Switch to the AC so the fans run whenever the AC is on. . . lol which is almost always here in FL. (The compressor quickly overheated running the AC while letting the engine warm up, waiting for the fans to kick on.) I could rig another relay to do the same thing, but there are already so many freakin' wires and relays under the hood with these trucks. So I think the plan is to see if I can retrofit a Trinary Switch from a later model GM vehicle to trigger the fans.

3. I love how much more visibility there is into the engine bay without the mechanical fan and shroud. I probably do need to fab up some kind of shroud for the new fans to help with airflow. Also need to get some bolts for the water pump so those old fan studs aren't spinning around like a wheel of death with the engine running.

In the mean time I'm going to go ahead and add a manual switch to ground the temp switch, so I can have complete control over when the fans are running.

I haven't driven it yet, but I'm curious to see if there is any perceptible difference in pick up and mpg.

Up next I'll be working to install the belly pan. I already painted the old sign I'm going to use, so I just need to put a couple bends in it and screw it to the frame.

 

Went for a test drive. "Seat of the Pants" Dyno says there's an ever so slight difference, but it could be in my head. I expected to notice more of a difference at higher RPMs, but seems to be the opposite. Felt like initial acceleration from a stop was better than before. Like it took just a hair less effort to get up to speed.

Here is where I mounted my relays, next to the battery.



Unused port on the water pump that worked perfectly for the temp switch install:



Here's a shot of the fans installed:


I did add a temporary manual switch inside the cab, so now I can make sure the fans are on if I run the AC. I'm hoping I won't need it after I get the cooler temp switch, and add the trinary switch for the AC.

Also I seem to have a small coolant leak from the water neck / radiator cap area. . . .So it might finally be time for a new rad here soon.

Once I put the belly pan on I'll go put a few miles on to see if there's any noticeable improvement in the MPG.

 

KnightBlazer, I am way way late to this thread but I really applaud you. You have MY FAVORITE year of this truck, a 1994.. your 1994 has the 3rd brake light. My 2nd favorite year, a 1993, does not. Other than that (and that the 94 i had had everything metric and Torx as far as screws, the 93 had all Philips heads etc... things like tail light housings etc. Weird little difference but hey..) this thread is awesome.

I have a 1996 now and I've exchanged about 15 quarts trans fluid a quart or two at a time over 5 months and it is running SMOOTH (and I will likely change every month or so) but.. the 94 and 93 still have my heart. I would even entertain a 92 or a 91.

Superb thread, sir!

 

Thank You! It's amazing how many things were different on different years of the 1st gens. Took me a while to find the correct versions of a couple things because of that, but I do love the 94. If I had the storage space and the funds I would be dragging home every cheap 91-94 I could find.