I have a 75 Scout II with a 345 v8. When started cold it turns over fine and fires up. After being driven for a while and engine is hot if I turn off and restart it struggles to turn over if at all. If left to cool it turns over and fires up. One time I went on a run turned the ignition off and it kept running wires began to smoke so I pulled off the hot lead at the battery. I left it to cool reconnected the battery and it started ok. I have replaced the starter twice and installed a heat shield around the solonoid. I had a mechanic do some work on it and he took off a fabric tube about 2 ft long that would fit around a pencil. I guess its insulation for a wire or metal tube.it has a silvery coating. Maybe this has something to do with it. The ignition switch occasionaly needs a key to turn it, other times not. I would like to put back the insulation tube even if its nothing to do with the problem but I dont know where it belongs. Im nervous to drive it incase it wont turn off and I cant get the hot terminal off the battery with the engine running.I also replaced the battery and the leads to the starter and ground. Should I put a shut off at the posative post of the battery. All advice welcome thanks.
hard turnover when hot
- Thread starter mr.b
- Start date
Scoutboy74
Moderator
This sounds like a hot start issue which is not uncommon in these vehicles. Basically what's happening is the current available to your starter and necessary to engage it fully when you turn the key is being adversely affected by all the heat. This is due in large part to the ancient, brittle and undersized wires which make up your current ignition circuitry. The most common fix is to incorporate a remote starter solenoid (such as those found on Ford vehicles from the 70's and 80's) in series with the battery and starter-mounted solenoid. Doing so permits full battery voltage to be transmitted to the starter during cranking regardless of under hood temps. At least one diagram outlining this process can be found within the confines of this forum.
The engine continuing to run with the key off is certainly a major cause for concern and indicates a serious problem with your wiring that must be addressed. Who knows what previous owner workarounds you May have going on there. You've already seen some precious smoke escape, which is never a good thing with regards to electrical systems. A wiring diagram from an IH repair manual that covers your '75 Scout would be helpful here.
The insulated tube you describe sounds like the hot air transfer tube which runs between a fitting on the top center portion of your passenger-side exhaust manifold and a fitting on that same side of your carburetor at the choke housing. This is part of the stock hot air choke system which is a precursor to the electric automatic choke systems in more common use today. They perform the same function, which is to restrict airflow to your carb during cold start and then gradually allow the choke to open up as the engine warms. The hot air choke transfers heated air from the exhaust to a bi-metal spring in the choke housing, while the electric choke transmits heat via battery voltage to a similar bi-metal spring so that the choke plate opens automatically in a timed manner.
The engine continuing to run with the key off is certainly a major cause for concern and indicates a serious problem with your wiring that must be addressed. Who knows what previous owner workarounds you May have going on there. You've already seen some precious smoke escape, which is never a good thing with regards to electrical systems. A wiring diagram from an IH repair manual that covers your '75 Scout would be helpful here.
The insulated tube you describe sounds like the hot air transfer tube which runs between a fitting on the top center portion of your passenger-side exhaust manifold and a fitting on that same side of your carburetor at the choke housing. This is part of the stock hot air choke system which is a precursor to the electric automatic choke systems in more common use today. They perform the same function, which is to restrict airflow to your carb during cold start and then gradually allow the choke to open up as the engine warms. The hot air choke transfers heated air from the exhaust to a bi-metal spring in the choke housing, while the electric choke transmits heat via battery voltage to a similar bi-metal spring so that the choke plate opens automatically in a timed manner.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
All of scoutboy's tips are right on the money. However....
A '75 sii would not have a hot air choke as an oem part, those went away with the step-up in federal/kali emissions specs beginning with the model year 1973 for all light duty motor vehicles (not just IH). So if you indeed have a functional hot air choke system, then it would be connected to a non-oem carb. That motor would have been equipped with a Holley 2210 variation which uses a divorced choke system.
Please post up some well-focused pics of the top of your engine so we can id everything in a positive manner. That is a must in order to work through stuff like this.
If the engine "runs on" or "diesels" when the ignition switch is turned off, then the distributor is grossly retarded timing-wise. And the most common cause of run-on is an idle speed which is too high (should be 650>700rpm in nuetral when hot). Significant vacuum leakage can also add to the run-on issue as well as an inop throttle kicker (only on selected models).
The "hot start" issue is common on all Scout II platforms due to the close proximity of the exhaust down pipe to the starter, thus IH added on the heat shield on the sii. Fullsize IH rigs don't have this hot start issue.
Also...there is no doubt that the entire wiring system needs attention, beginning with the bulkhead connectors. You will find the 10 gauge terminals in the bulkhead connector is really fried, that must be cleaned up and re-worked or you will deal with electrical issues on a regular basis. Same for the connection points on the starter solenoid terminals.
I replace all battery cables with a minimum of 2 gauge (4 gauge was oem). And I install a "bonded" ground system (very simple) which means that the body is grounded to the frame, the frame is grounded to the engine block/starter, and the battery ground goes directly to the engine block. All ground cables on the battery side must be the same gauge as the positive cables.
Every IH vehicle I work with gets a remote starter relay added into the system as trever describes. There are many reasons I do that...it will not "cure" a heat-soaked starter issue (but the heat shield certainly helps!!), but it does upgrade the electrical system.
See this thread for some additional info regarding a workout for the very inadequate IH-produced electrical system on these vehicles:
http://www.forums.IHPartsAmerica.com/electrical-tech/2529-switchable-dual-batteries.html
A '75 sii would not have a hot air choke as an oem part, those went away with the step-up in federal/kali emissions specs beginning with the model year 1973 for all light duty motor vehicles (not just IH). So if you indeed have a functional hot air choke system, then it would be connected to a non-oem carb. That motor would have been equipped with a Holley 2210 variation which uses a divorced choke system.
Please post up some well-focused pics of the top of your engine so we can id everything in a positive manner. That is a must in order to work through stuff like this.
If the engine "runs on" or "diesels" when the ignition switch is turned off, then the distributor is grossly retarded timing-wise. And the most common cause of run-on is an idle speed which is too high (should be 650>700rpm in nuetral when hot). Significant vacuum leakage can also add to the run-on issue as well as an inop throttle kicker (only on selected models).
The "hot start" issue is common on all Scout II platforms due to the close proximity of the exhaust down pipe to the starter, thus IH added on the heat shield on the sii. Fullsize IH rigs don't have this hot start issue.
Also...there is no doubt that the entire wiring system needs attention, beginning with the bulkhead connectors. You will find the 10 gauge terminals in the bulkhead connector is really fried, that must be cleaned up and re-worked or you will deal with electrical issues on a regular basis. Same for the connection points on the starter solenoid terminals.
I replace all battery cables with a minimum of 2 gauge (4 gauge was oem). And I install a "bonded" ground system (very simple) which means that the body is grounded to the frame, the frame is grounded to the engine block/starter, and the battery ground goes directly to the engine block. All ground cables on the battery side must be the same gauge as the positive cables.
Every IH vehicle I work with gets a remote starter relay added into the system as trever describes. There are many reasons I do that...it will not "cure" a heat-soaked starter issue (but the heat shield certainly helps!!), but it does upgrade the electrical system.
See this thread for some additional info regarding a workout for the very inadequate IH-produced electrical system on these vehicles:
http://www.forums.IHPartsAmerica.com/electrical-tech/2529-switchable-dual-batteries.html