Well, that would somewhat explain why my engine is running hotter now. Because what I described is exactly what I did. I took it from about 8 to 4 Deg BTDC. Thanks Bill. I'll keep working on it.

 

Eric,
One last thing...I have gone through probably three termp gage sensors in the past 10 years. I would highly recommend changing out the currently installed sensor (they are readily available at any major auto parts store; I use NAPA and put on a good connector on old wire going to the new sensor. This sensor uses impedance to ground to make the gauge work and there is a gauge transformer which is bolted behind your instrument panel which controls the factory gauges. I have literally done a dozen frame off restorations on 78=79 Bronco,'s and F-250's, including complete rewiring and drivetrain remanufacturing. I am a full-time electrician and a part-time mechanic, and have over 30 years experience (if you want to knpow my qualifications). Everyhting I've told you is based upon at least 10 years of experience in daily driving these vehicles. I have only had to fool with the timeing on one 400 which I had pulled out of one of my six Mark V's toi use in a 250. For some reason, that 400 never did run right in the 250 and we just changed it to another one and had no more problems. I am trying to give you the benefit of my countless hours of trial and error.....feel free to take them or leave them.

 

Going from 10 degrees BTDC to 4 degrees BTDC retards the timing.

Any time you change from more degrees BTDC to fewer degrees BTDC, the event (spark, in this case) occurs later in the cycle, and relative to the original position, it is said to be retarded.

If you were looking at an event that occurred after the piston passed top dead center (ATDC), then changing from more degrees ATDC to fewer degrees ATDC would advance the event (i.e., make it occur earlier in the cycle).

 

Lisagoud,
Changing the temp sending unit and connector was one of my remaining 'cheap' jobs left to make sure that I'm getting a correct temperature reading. I hadn't even tought about changing anything behind the dash though, since I didn't even know there was a trandformer back there. Obviously my experience is far less than most of the people trying to help me out on this one eh? That's why I'm here, so you guys can point me in the right direction. So, as for your advice, I'll take it. Thanks!

Bubba,
Thanks for your advice as well. I thought advancing/retarding went the way you described it for BTDC settings. So, if I retarded my timing (from 8 to 4) why would that make it run hotter than before? Could it be the air/fuel mixture isn't right for the timing I set it to and now it's burning hotter (I got this idea from your website)? Well, I'm going to start messing with the timing to start with, change out a few more little items that are involved, and then maybe try my luck with carb adjustments.

By the way, does anybody think removing the air-conditioning condensor from in front of the main radiator will make much difference in running temps? Thanks.

 

There is no "transformer" behind the instrument cluster, (you can't use a transformer on DC). There is a Instrument panel voltage regulator which is like an emergency signal flasher. The "voltage flasher" applies system voltage to the gages like a signal flasher, it averages out to about 5 volts if you check it with a scope. This IP voltage regulator can fail to flash OFF enuf due to a buildup of oxidation between the ground contact and the flex circuit. This failure will result in higher average voltage to the gages which will make the fuel gage, oil pressure, and temperature to read higher than normal. The cure is usually cleaning the surface of the flex circuit and the mating surface and connectors. Coat them all with a thin film of silicone dielectric grease before assy to prevent oxidation in the future. The connections to the ammeter also get oxidized and the ammeter will no longer register any charge/discharge current. Cleaning all of the gage contacts with the flex circuit , and all of the plug in type connections will make your ammeter and other gages work better. Make sure that all of the crimp wire connections are clean and solder them if at all possible. The IP voltage regulator and gages are all affected by ambient temps so the gages don't read the same under all conditions.

There is more information on these gage clusters in the 73-9 truck forum and also possibly in the Bronco forum.

Removing the condenser will make very little change in your running temps unless of course the AC is on...

Get your system cleaned out good, make sure nobody has drilled out the restriction under the stat. (I have seen both cast and plate restrictors and I never correlated them to specific engines having one or the other, Bubba knows more than I do about the differences). I have seen the cast restrictors broken/drilled out tho... Make sure you have the proper ~195F thermostat with the "skirt" on it that is required for these engines. A Robert-Shaw HD unit is what I use available from Auto Zone. Do not use the Stant thermostats (they fail easy). Get a HD clutch type fan from the salvage yard also.

You don't have a high volume aftermarket water pump do you?

Make sure your timing marks have not moved. The damper assy can go bad.

 

Torque 1st,m
Thank-you for the clarification for the voltage regulator, I've always felt the term transformer was mor easily understood by definately is not technically correct. I think we are all telling him the same thing with the following discrepancies:
1. I was not aware of the Stant thermostat problems
2. I don't think anyone has talked to Eric about the need for verifying the condition of his factory waterpump (not high volume). I have seen lots of waterpumps with the vanes eaten right off.
See, I managed to learn something new with this conversation which, after all, what these formus are supposed to be for. (Everone helping and no one trying to run the show).

Eric, I think you have a problem which sometimes can be difficult to be caused by just one problem. I think you may have a bad pump combined with perhaps a radiator problem. (either bad flow or not enough cooling ability thus 4 rows or the super 3 rows should be enough. I wouldn't worry too much about the instrument panel voltage regulatyor since I think they're are more likely cauises that you could check first before woorying about that.
Good luck

 

Thanks for the correction Bubba, evidently I've spent too much time on this computer lately and not enough working on my truck. I was thinking about it from the wrong side of the cycle. Glad you caught that.

 

im running a 400 from a late 77 in my 79 f-150 fulltimer , ended up with a radiator out of my 79 f250 with 460, still runs on the warm side, ive owned this truck since 1984, always did run warm. just thought id put in my 2-cents good luck

 

Watch those cheapo rebuilt water pumps. They have a stamped metal impeller on them in place of the original cast iron one. They won't pump nearly as much.

My '75 Merc Bobcat with the 2.8 always ran hot. When the water pump went bad, I noticed right away that it had the cheap rebuild on it. I replaced it with a good one and my water temps dropped 30 degrees.

I'd advise getting one of those inexpensive gauge sets from Walmart and at least hooking up the water temp gauge. Then at least you'd know what temps the engine really is running.

 

Thanks again everbody. I know that overheating or running hot is a little ambiguous and I will need to check several things to narrow it down. All your input has clarified a lot of things I was thinking about and brought up a lot of things I hadn't even thought of. Now I just need to get on some warm duds and head out to the truck (it's getting cold here in Michigan finally).

Now my questions....I assume tho only way to verify the state of the water pump is to remove and inspect it right? The old squeezing-the-radiator-hose-to check-for-flow trick is probably not of much use.

Also, a few of you have mentioned new radiator and fan as a possible solution. What's something like that run for price typically? I really want to get this figured out so I can then focus on enjoying the Bronco. It sucks driving and having to watch my gages all the time. But then again, working on the old beasts is part of the fun too I guess. Anyway, thanks for all the help and any other tips you can think of. Happy Holidays!

 

Eric,
I would check with a local radiator shop on the chance he could just recore and use you existing tanks of your current radiatopr. A quick check of my favoriute on-line source says extra cooling complete for $185.00 or, the one I use, Super cooling for $295.00. The nice thing is, once you replace your radiator, you should be good for a long time to come.

 

A three core radiator should be plenty for a mostly stock engine that is not doing any HD towing etc.

A slipping auto tranny can dump a LOT of heat into a radiator also.

It is possible to get too much water flow thru an engine.

lisagoud- I am glad you found something useful in the instrument panel voltage reg explanation

The instrument panels in the older trucks are usually in pretty bad shape and need lots of work to make them work correctly. I think it looks better to have the OEM gages work well so you can have some confidence in them, rather than installing aftermarket gages that look so tacky (IMO). I have seen a couple of nice installations but they are rare.

 

Torque ist,
I agree 100%...whenever I have factory gauges to work with, I always use them. I have had to change out the instrument panel voltage regulator (see, I called it by it's right name) upon rare occasions, but, usually it's the sensor or the wiring connection that is the problem. A simple way to check the gauges, as I'm sure you know is to have someone watch the gauges while you ground out (momentarily) the sender wire. The gauge should (temp and oil) read the highest mark. If it doesn't, I would ohm check (with an Analog meter to simulatoe actual load resistance) the wiring harness from the gauge to the sender (with aot of attention paid to the plug in type conectors Ford Uses)...Most of the time, the pin is either all corroded or the female insert pin is the same way (I have soldered bypasses upon certain occcasions and I have also soldered in new connectors depending on the damage to the rest of the harness)....even thopugh the new school of thought advocates just using crijmmp connectores to avoid any potential overheating problems to the rest of the harness...I feel this is easily avoided by always using a 'heat sink'). I agree with the generous use of dieelectric grease....It's beats the hell out of some of the items we used to use 30 years ago. I'm also noticing that little tubes of it are coming with just about every electrical part I pick up from my favorite Auto Source.....Anyway, I think Eric is well on his way to solving his problem and has learned a great deal on the simplicity and durabilty of these great old (not to me...I have to keep telling myself that 1979 was almost 25years ago) trucks. Happy Thansgiving everyone.

 

The original crimped connections in our vehicles are fine for a system that is only supposed to work for 5-10 years. Unfortunately heat and moisture take their toll on the connections. Soldering or using dielectric grease extends connection life. When I refurbish an electrical system I clean all of the contacts and solder all of the connections that I can. I pull the other crimp connections apart, clean, re-crimp, and solder them. I replaced one IPVR but when I did I determined that the real reason for it not working was oxidation of the connections and the old part was OK. After that I have not had to replace one, -I just clean the connections. When you just replace one it makes new contact with the flex circuit and "works"... but not for long Our instruments are particularly susceptible to oxidation of connectors because of the low voltage and currents involved. The instrument panel is only part of the suystem, ALL of the connections thru the entire system, plugs, connectors, sensors, etc etc have to be refurbished.

Have a fine turkey day!

 

Well I hope everybody had a nice Thanksgiving. I definitly did, but I didn't get much done as far as sorting out my overheating problem. I posted several other threads over the weekend and out of one of them came the idea to try disconnecting the vaccuum line to my EGR valve (not for overheating, for other reasons). So I did and to my suprise my engine seems to be running cooler. How is that possible? I thought EGR in part, was to help reduce combustion temperatures. I've only done one test drive so I'll learn more tomorrow but I just wanted to throw this out there to see what somebody thinks.

Also, is there an effective, relatively inexpensive test to determine if my radiator cores are junk? I'm really leaning toward a new radiator but would spend a few bucks to have it checked first if it could save me $100. Thanks for any advice.