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Blew another seloniod on 1976 Ford 302

N

Neal Franson

New member
I did some exploratory and found that the black 8 gauge wire attached to the starter side of the selonoid is the negative ground to the gauges, and the red 8 gauge wire on the battery side powers up the key switch (B) and the gauges. Still not sure where the wire from the (S) terminal goes, except to the yellow plug which looks like it goes to the console, but it didn't seem to make any difference when I disconnected it, so I hooked it back up.
I didn't find any fryed wires anywhere, but did clean up a few connections. It still was a slow crank and only about 10 seconds of crank at all, the last time it was cranking.
I went to start it today and nothing except a single click from the selonoid. So I will have to get selonoid #5 just to get it to turn over.
Any ideas, let me know.
302 schematic as-is.jpg
 
The wiring is old, and when I cut the wires back to put on a new connection, they seem somewhat dark and corroded. I am wondering if I should just re-wire the whole thing, maybe get new gauges (although they seem to work fine)? All the high amp wiring through the selonoid is new, clean and huge from the battery to the starter (02gauge).
 
I stands for ignition and S stands for starter on marked solenoids. The S post on the solenoid is coming from the key and is what activates the solenoid. If you touch a wire between the S post and the battery side post the solenoid will activate. You can also buy a solenoid with a button to activate when in the engineroom. The only reason I can see for a new solenoid to fail is either the wrong voltage or a bad connection. When searching for a bad connection, remember to check the ground, too, all the way back to the battery neg post.
 

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Thanks for your reply. I do have a remote switch to jump the + and the (S). As far as wrong voltage or bad connection, do you see anything on my schematic around the selonoid that looks suspicious? Any wrong connection?
 
Your BLACK 8GA wire coming from the Gauges should go to the engine block and NOT the Starter. Depending upon what else is going on at the console, this change yield a substantial improvement...

Don't know what is at the console that requires a BATT connection, but I would be inclined to supply a separate (protected) lead for those loads.

I would also suggest that the ALTERNATOR output (ORG 8GA) go to the starter solenoid's Battery connection (or battery itself)....There is no reason to try to move that much current thru the key switch.

Verifying the ground wires are in good shape, as Lepke suggested, would also be a good net step....I would also suggest getting the battery load tested to make sure its delivers adequate current.

Probably a good idea to pull the spark plugs and make sure the engine will turn over easily (by hand)...if the internals are damaged, the slow crank may not be unexpected...

If the slow crank continues, I would suggest making voltage drop measurements to find the culprit(s). Typically you can also use an IR gun on the starter circuit connections....high current draws thru bad electrical connections = Lots of Heat....
 
and the 'yellow plug' may go back to the shift control and be part of the neutral safety switch wiring...that appears to have been bypassed based on your diagram...

finally, excess current typically kills solenoids by eroding their contacts prematurely...the only thing I see is that 8Ga black wire tied to the starter's lead on the solenoid...you can do a quick check by measuring the battery voltage (fully charged should show 12.8VDC or better) and then checking the voltage between the negative post on the battery and the solenoid lead feeding the starter while cranking....if it drops below 10VDC, that suggests excessive current draw....
 
Wow, that's great! I thought that black 8 gauge wire was the culprit. I was also puzzled why the alt output went to the key, and right back to the selonoid. I will do those changes for sure and go from there!
I have done load tests on the battery and they check out in the green. Also various load tests for slow crank around the selonoid, which came out bad, probably from the black wire.
Thanks again!
 
I am waiting for the new selonoid from Amazon, but made the changes to the wiring with the black and orange 8 gauge wires and also updated the schematic:
302 schematic as-is.jpg
 
Dang! Still slow crank and only 15 seconds of crank time. Mark, I thought you really had it wired! All of your recomendations aligned with what I suspected.
Asside from re-routing the black and orange 8 gauge wires, I also re-routed the other accessories the were hooked up to the batt terminal on the key switch and also disconnected the ancient fuse block that was also attached to the gauges, so there is little left that would cause a drain of current that I caan see.
I guess I will re-do the load tests for slow crank and see if I can make any sense out of it with the new schematic.
Good news, the new selonoid has 30 seconds of use on it and hasn't blow out yet!
And perhaps pull the spark plugs, as suggested. It is a newly re-built un-broken-in engine, It has never been started, so I would expect it to be a bit tight, but....
I could do a compression test, just to ensure internals are okay.
Any other ideas?
Here is the updated schematic:
302 schematic as-is.jpg
schematic.
 
I wouldn't worry about a compression test until the starter will spin the engine at a 'normal rate'....Doing a spin check with the plugs out would let you know the engine isn't dragging (mechanically)....since you mentioned 'newly rebuilt' - have you primed the oil system? checking the initial timing would also eliminate another 'rebuild variable'.

If I were doing the detective work, I'd check the starter draw (as is) ... If you don't have a high current amp meter, next best thing would be a voltage drop test done along the current path for the starter...do each component between the connections and start with the ground lead to the block...given the age of the engine, the wiring may be degraded - looks fine on the outside but corroded on the inside. A qualitative alternative is to run an IR gun along the path (while cranking) looking for a hot spot...

Did you mean the new high current cables are 2/0 AWG in size or just 2 AWG - I've never seen "02" used to quantify wire size...??? Are they made of Marine Grade cable?
 
I haven't primed the oil system, I am kind of a YouTube mechanic, but I did find out how to do that, taking apart the distributer and hooking up a drill to spin it at high RPM.
The timing is close, and not the common mistake of being 180 degrees off.
I can do the voltage drop tests.
Some wiring looks a bit dark when I put on a new connection. Replacing secondary wiring may be after other checks.
The primary 2/0 wire is much bigger than 2. It goes 2, 1, 1/0, 2/0... I got them at Harbor Freight, so not marine grade, but huge. I recall the load test from battery to the selonoid battery connection was a bit low, It was .3, when it said it should be less than .1, and the test from battery negative to engine ground was .7 and said it should be less than .1, so maybe replace both.
Thanks again!
 
your diagram labeled the 'big' cables as "02" which is why i asked the question.

FWIW, I wouldn't have gone to HF for battery cables, especially for a boat...but that is your choice.

Not sure what you are referring to as a "load test" - given those details, it sounds more like a voltage drop test....and <=0.1VDC drop between adjacent nodes is reasonable...in a properly operating system...
 
Yes, of course, you are right, it was a voltage drop test. I am ordering some new battery cables, since the drop of .3 and .7 were not adequate.
I will do the four voltage drop tests for slow crank again after new battery cables.
Also will pull the spark plugs to ensure motor is okay. I may go ahead and do a compression test to ensure the overhaul is good.
I will prime the oil system.
I may wait to replace the secondary wires, unless you think it is an important issue. I think it was mainly the ingnition line from the key to the selonoid and the ignition to the choke that I recall were dark and somewhat corroded. Okay, sounds important. - I will replace with 12 ga.
I believe you are right about the starter wire from key to selonoid bypasses the shift cut-off, so do I still need that wire to the yellow plug from the (S) terminal on the selonoid?
Any other suggestions?
 
i don't see how you get an accurate compression test without the starter turning over the motor at a 'normal' RPM...

I would hold off on changing the plug wires until it is running and past the initial break-in point...especially if there is a new cam in the block...but thats a different topic...if there is a new cam, do a web search on "breaking in a flat tappet camshaft"...

given the age, it may be faster (in the long run) to just replace the harness(es). That said, if you found some darkened wires, they will be detractors so eliminating them is never a bad idea...if you don't plan to replaces the harnesses, use marine grade wiring - the tinning it has delays that darkening for many decades...

The shift cut-out is NOT the same thing as the neutral safety switch...that switch opens the circuit between the key switch and the solenoid when the shifter is not in neutral...so it really needs two wires...that said, I've haven't been into an old OMC harness in a long time so they may have done something differently in that timeframe.
 
The wiring harnesses are not available at marineengine.com. They don't have the battery wires, either. I will have to find some somewhere.
I don't think they put in a new cam.
My thought on the compression test was, if the plugs are out, the starter motor would turn it over at a good rate, and as long as they are all about the same, it should be okay.
 
You may not be able to by an original harness...if you are handy you can just replace the wires one at a time...from the engine to the dash (or where ever else they go)... the only drawback is you loose the 'connector' which is only an issue if you have to remove the engine again....

Your HF wires should be ok for the short term...assuming the ends were crimped correctly...my observation was intended to tell you they won't last anywhere near as long those made from the appropriate material...

If they reused the cam and lifters, then you don't have to worry about a break-in...

It won't hurt to try the compression test as your last post states...I'd be inclined to pull ALL of the plugs and spin the engine over and getting the oil galley filled...and then putting in the compression tester...but don't know all of the details since the rebuild so it may not matter at this point...it sure won't cost you anything but time.
 
My 302 has GT 40 heads, which bumps it up to 190 hp from the 175 of the standard heads. I believe that that means that it has roller lifters, but not absolutely sure of that or exactly what they replaced. So if I spin the engine with the starter with the plugs out at a good rate, will that prime the oil pump and get the oil throughout the engine? Or I need to do it the other way by spinning the oil pump connection with a drill using a part of the distributer?
I have ordered the new battery and starter wires in 1/0 gauge, which is also refered to as zero gauge, (0 AWG). all custom made in tinned copper marine grade, and the connectors are also tin plated. I also ordered the ignition wire, key (I) to selonoid (I), in purple 12 gauge, which, yes, will not go though the plug. I may also replace the starter wire, key (S) to selonoid (S). About the only other wires that are not new is the selonoid to the carb choke, the voltage regulator to the key (I), the oil and water sensors, and the orange 8 gauge alternator to selonoid (bat), which I cut off a section that went to the console that looked to be in very good shape. Oh, then there is the selonoid (S) to yellow plug, that we are not quite sure of (probably to remote). Any of those that may cause a slow crank that should be replaced? Is it a good idea to bump up the wiring from 14 gauge to 12 gauge? I figure there is less chance of frying a wire, but maybe higher risk of frying the component.
Every component on the engine is new, except the alternator, which is chrome, so I kept it.
 
On spinning the engine, yes, that will get the oil moving...just don't overheat the starter...crank for maybe 20 seconds, then give it two minutes to cool and then repeat...using the drill is faster...but requires more effort...

The starting circuit high current path includes three battery cable s< 1) from the battery to the solenoid, 2) from the solenoid to the starter, & 3) from the block to the battery (the ground cable) > and the solenoid & the starter. I would say if you ordered three 1/0 cables, you got that ok.

If the wiring is properly protected, neither the wire or the component should get damaged...Upsizing a given conductor never hurts except for the initial purchase...There are many Conductor sizing charts available for low voltage DC applications...the 3% max voltage drop size recommendations would be very conservative. For your engine, the 10% max drop recommendations would be typical and I'd say 14 AWG is adequate for everything going to the dash except for the RED and BLK leads which would likely be 10 AWG.
 
I saw my grandkid, too.
I put in the new 0-gauge cables, took out the spark plugs and spun the engine with the starter, and same slow crank!
I did it for 20 seconds for 7 or 8 times and it didn't speed up, just got slightly slower as the battery ran down. It did still crank at 12.3 before it got quite slow, which is better, and may just be attributable to no plugs, less resistance.
I went ahead and did a compression test, as it is really hard to get the p[ugs out with the GT40 heads and the oversized exhaust manifolds. The results were #1 - 70 psi, @2 - 80 psi, #3 - 70 psi, #4 - 70 psi, #5 - 90 psi, #6 - 90 psi, #7 - 92 psi, #8 - 65 psi.
This may not tell me anything, as the oil still may not be distributed throughout the engine, and any other variables, from the re-build but it is about a 30% variance.
So, I don't know if I got the oil pump primed - seems it should run faster, if I did. So assuming it is not primed, should I spin it through the distributer? I guess. Any other ways of telling? I don't want to take off the valve covers just to tell, as I would first have to take off the heavy oversized cast iron exhaust manifolds.
Other possibilities on the slow crank:
1. wrong starter. The last one did the same. It is for a 70's Ford 302 marine OMC, has nine tooth drive gear. Not sure if I have 157 or 164 tooth ring gear - I did count them once and it seemed it was over 160, as I recall, but not sure. This one says it is for a 157 tooth , and cost about $100. Is there any point in getting a $400 one? Maybe I should call marineengine,com and see if I can get the right one. This is from the one I have:

New Professional Grade Starter Compatible with Ford Marine & Crusader Various Mercruiser Stern Dri Model 888 1971-77 OMC 5.0L 5.8L Waukesha 302/351 1971-76 D5FF-11001-AA D8FF-11001-DA E1JF-11001-AA​

2. Still some electrical problem. I am waiting for the new wiring for beween the key and the selonoid. Could check the batteries again. I do have a tester that checks under load, as it has a little heater to simulate a load. They are both large and about a year and a half old AGM batteries. They do seem to fully charge to 13.6 volts, but do seem to rundown quickly. I have tried hooking up to my Ford F150 battery with the same results.
3. Some internal problem from the re-build, (worst case scenerio). I would have to finish off the oil pump priming and the other electrical, and perhaps the starter and anything else I could think of, as I have been the mechanic on putting everything back together from the raw re-built engine block. So it could be from other things I may have done wrong.

Any thoughts on how I should proceed? Or any thing else that may be awry?
 
did you do the voltage drop test in the starter's high current path? check for excess heat at the junctions?

what is the ratings on your batteries CCA/MCA/AHrs, etc?

It won't hurt to prime the system at this point...I'm thinking there is still something dirty in the starter's high current path...
 
I haven't done the voltage drop tests, yet. That's probably next, maybe put in the new wires to the key from the seloniod. That way everything is new, New key switch, starter, selonoid, wires and battery - that is about all there is to the starting circuit. That is why I suspected maybe I have the wrong starter, especially when it had the same slow crank without spark plugs - seems it should have spun!
I did email marineengines.com, and they just referred me to the engine manufacturer, and didn't say anything about the number of teeth in my ring gear.
Should I buy an Infa Red laser thermometer from Harbor frieght for $25?

Batteries: Autozone

Duralast AGM 31M-AGM Group Size 31T Dual Purpose Marine and RV Battery 875 CCA 1030 MCA​

about a year and a half old. They are only guaranteed for a year.

And Optima

Optima BlueTop D27M Group Size 27 Deep Cycle and Starting Battery 800 CCA 1000 A MCA​

It is about 3 years old, but they are supposed to last a long time.

I have considered getting a new Optima

Optima BlueTop D31M Group Size 31 Marine Battery 900 CCA 1125 A MCA​

and putting it together with the other Optima blue top in parallel, instead of the Duralast, but when I switched to my truck battery and the same thing happened, I kind of ruled out the battery as the problem. It is a $400 battery.

I can do another load test on the battery.

One question on the wiring: The purple wire that comes from the voltage regulator, can I hook it up directly to the seloinoid (I) terminal, instead of going all the way to the key (I) via one of the gauges, I belive the volt meter? I believe the (I) terminal on the selonoid isn't wired to anything in the selonoid, but is just a connection node and is powered from the wire from the Key (I). Correct?

Re-wire the key with new wires, recheck batteries, drop tests through the starter circuit, maybe check for excessive heat with IR tester...
 
IR thermal guns are very handy ... I think they are great for debugging...

Is there a good starter & alternator shop in your vicinity? I would think they could test the starter and tell you if it spins 'normally' - if it does, then you still have a wiring issue or two to resolve.

I don't see the need for another load test in the battery as you said you have ruled that out...

On the solenoid's "I" terminal, its purpose is to supply +12VDC directly to the coil while the starter is engaged...

On the purple wire, I'm not sure of its function...that said, moving it to the I terminal on the solenoid with no other wires going to that I terminal will effectively isolate the purple wire - likely keeping the alternator from working...
 
I'm not sure that you got my concept on the purple wire. You have to look at my last schematic, The purple wire from the voltage regulator heads towards the key switch (I) via the purple wires feeding the gauges at the volt meter. The key (I) terminal has another purple wire that heads to the selonoid (I) terminal, giving it 12 volts when the key is turned on. Like the orange 8 gauge wire, it seems like a very circuitous route. I would understand it if it went to an ammeter, but I don't have one. So if it was hooked up to the (I) of the selonoid, it would still go on to the Key (I) and onto the gauges, all purple wires, as well as to the coil and carb choke, all getting their 12+ volts, which it would, as it is, going though the console.
There may be some reason for this that I am not getting. I think it just goes there in case I had an ammeter.

Note, the last starter did the same thing, that's why I got this one. Is there anyone who can tell me (or how to find) what the correct starter is for my engine? The engine serial # is: W524031. The OMC model is #990231M. (1976 Ford 302 CID Marine 190 HP) I just Googled that and got all kinds of answers, including the starter that I now have. Maybe one of the marine shops can tell me.
 
Your plan on the purple wire re-route makes sense with the extra detail.

As far as anything tied to your Ford, they have been standard production for the marine environment for decades. finding a part isn't hard as most everything that fits the 302's fit the 351's...a lot of people are reselling imported junk...and, unfortunately, a lot of those have very short service lifetimes...you can get the ARCO or API catalogs online and look up your starter type.

Re-reading a few posts back, you said you were showing 12.3VDC on the battery after a short period of time...a fully charged battery should show 12.8 and should be able to maintain it for many cranking cycles...if its dropping, that suggests the battery is marginal (or was charged marginally) or you have a marginal cable or connection. The voltage drop test will help with the latter.

Finally, if you take your starter to a good rebuilder or supply house, they should be able to do a functional test for you...
 
I'll re-wire and do the tests this weekend.

I found a Sierra Marine starter at West Marine that says it is compatable with most OMC Ford 302s and 351s for $257.99 and is rebuilt. Not sure I want to go there. I'll do the tests.
 
If you have a duralast battery, that suggests you have an autozone close by...they should be able to bench test the starter...
 
Understand...did a little digging and found you need to know what flywheel and ring gear combo you have to ensure you get the correct starter on the SBF's....

Have you ever had the engine running - in other words, did you rebuild it or did you acquire it after the rebuild? Getting at the possibility that the OEM flywheel may not have been used...

Does the starter make any grinding sounds when you engage it, trying to crank the engine?
 
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