When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a '78 Bronco that is becoming more difficult to start.
The issue has been going on for awhile, but is now very bad. The starter will turn over very slowly even with a new battery, new starter and new solenoid. Engine is new, and turns over freely as well as a new tranny rebuild.
It did this for years but now I need to find the culprit. Starter relay gets so very hot that it has actually melted the plastic housing. Also, even when switch is off, sometimes dash lights will stay dimly lit.
Seems to be worse when engine is warm, but can do it anytime, cold or warm.
I have no idea of where to go.
Any help would be appreciated.
have you replaced the battery cables with good quality 1 gauge wire. Also you might have a bad coil , and or distributor. What size motor do you have in this bronco??
Yes, all new high quality cables - new positive to soenoind, new ground (grounding to block), new starter to solenoid, and new ground (bonding) strap from engine to frame.
Engine is big block, 460. Has been in the bronco since we bought it new in '78. Took the 351M out while still under the factory warranty and put in the big block.
Also new distributor, and coil.
Any other ideas?
Yes the timing is good. It is an electrical problem IMO, though I don't know where to look.
Sometimes it will spin it up with no difficulty, then other times it would barely turn the motor over, not fast enough to start it. Even when jumping it off from a strong battery/vehicle, still same deal. When the starter is turning very slow, it will literally melt the solenoid housing it's pulling so much power through there.
Thanks for the input though.
Pulling power isn't what generates heat - it's resistance. Whatever gets hot has too much resistance. Clean it, tighten it, or replace it. The only thing that SHOULD get hot is the starter motor itself, but it should only be used in short bursts, so the heat doesn't really matter. (I've driven short distances on mine, but that's another story. )
To find the exact cause of a slow starter, just get a cheap $10 digital multimeter from Wal-Mart, Sears, or Radio Shack and start looking at voltages WHILE cranking: 1) across the battery (should be 10-12V); 2) from the relay's BATT terminal to the STARTER terminal (should be ~0V); 3) from the starter terminal to the block (should be the same as the battery); 4) from one end of the starter wire to the other (should be ~0V).
didnt notice if you replaced the starter? if not i would check what steve83 says first then i would check to see what your amp draw is while crancking. i believe your draw would be very high which is causing your solenoid to get hot as he**. are your battery cables clean tight and of the correct gauge? an under sized wire will also get hot. is the ground to the engine block clean and tight. in my opinion it is probably bad connections or the starter is bad.take your time and troubleshoot it correctly the first time.
Yes the starter is new.
Cables are new, all of them including the pos. to solenoid, neg. to block, solenoid to starter and a grounding (bonding strap) from engine to frame.
Will check the voltage as you and steve suggest.
Thanks for all the help guys, cause this has been driving me crazy. Just decided it was time to put it to an end.
If the voltages check out OK, I would suggest getting a high torque starter. I had similar problems with a 429 I had wedged into a Mercury Cyclone. It would actually melt the insulation off the battery cables. After going through 4 or 5 regular starters, I finally spent the bucks and got a good high torque one. Never had a problem again.
Another thing to check is the size of the battery. I know that made a big difference in my bronco. It was hard to start and would act like your's does. I got a battery with high cranking amps and it helped a lot.
just a thought....
Steve,
Okay I have part of the answer....
When I checked battery voltage on bench it was around 11.0~11.5 vdc.
I hook up the battery to the starter solenoid and then hook up the ground(neg. cable). Got sparks and heard the starter click, not the solenoid but the starter, kinda like the bendix was trying to engage. Decided to check the solenoid, and I have a closed circuit on the In~Out of the solenoid (across starter post and batt post) when off the vehicle.
I also noted the battery voltage was immediately pulled down to about 2.0~2.5 vdc. When I disconnected the negative cable from battery post, battery voltage was back up to around 11.0 vdc.
So, I have now replaced the starter solenoid (although it was brand new). Motor will spin up with little resistance (poor choice of words) sometimes and crank right up then it might barely turn the engine over the next time.
What thoughts are next?
The tests I suggested should be done with everything installed normally, but I'm glad you found part of it. The battery voltage sounds REALLY low, so I suspect a bad or discharged battery. Charge it for SEVERAL hours and repeat the tests. If it won't take a charge, it's the battery. If it DOES hold ~13V at rest but drops below 9V while cranking, it's the starter. If the battery is more than ~2V higher than the starter while cranking, it's high resistance between the two.
This may sound weird but I had a similar problem with my 79' and it turned out to be a neutral safety switch, since then it's started great. Have you thought about a dual battery setup, I find it definately to be a good investment especially if you run a winch or a large stereo system.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.