12.7 tough spin when cold

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by stonefly4, Nov 30, 2020.

  1. stonefly4

    stonefly4 Light Load Member

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    I think I'm getting coolant into a cylinder, via an old head gasket, but I don't know. I'm not sure. I wondered if anyone has experienced the problem.

    At first, about a year ago, it happened only once, when the temps were down in the low 20s. Now it's happening in the low 30s.

    If the engine is warm, it spins a few seconds and starts right up. It's about to get into December and the engine gets cold enough when sitting for a while that it will spin for a second or two and then "thunk"—the spin comes to a dead stop. When I immediately re-hit the starter button, all I get is "thunk"—no spin. If I hit the switch enough times, and the engine passes through enough "thunks" or stops, then she'll spin normally and start.
     
    Last edited: Nov 30, 2020
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  3. Rideandrepair

    Rideandrepair Road Train Member

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    Are you adding coolant? Is there any white smoke after idling? I would check the starter relay wires. Rule them out. If it’s a Freightliner, the selinoid on the firewall wires are prone to breaking. Leaky injector cups will cause a cylinder to lock up,while starting, eventually getting worse, and won’t start. A dropped liner/ leaking head gasket also. But usually will blow the gasket, once you’re suddenly adding over a gallon per day. Happened to me, liner dropped, head gasket blew, engine locked up. A pinhole in a liner, depending on the location, and location of the piston on its stroke, could cause it intermittently. An oil analysis would show any fuel or coolant. If it’s enough to cause a lock up, I imagine some would wash down past the rings, and show up in the oil.
     
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  4. MRMTRANS

    MRMTRANS Light Load Member

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    I used to have what sounds like a similar problem on a truck I got rid of years ago. I had to crank it thru a hard start so it wouldn't die after it seemed like it was going to keep running. Of course it only happened when it was cold. It even had a block heater plugged in. I heard that low compression pistons (15:1 ratio) have hard starts in the cold. I don't remember the model number (either begins with PK or BK) on the side of the block, but you could check to see if you have that one. On my truck, I never really had that problem until I had it rebuilt. I noticed I didn't have as much power after the rebuild either. I concluded-years later -when I learned about low compression vs high compression pistons-that the dealer didn't rebuild to original spec. In fact I heard that when they did rebuilds then (in 2002 in my case), they automatically put in low compression kits-and reprogrammed the ECM- for emissions because they got caught cheating on their testing submits to the EPA on the development of their newer engines mandated to be installed on future trucks.
     
  5. blairandgretchen

    blairandgretchen Road Train Member

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    All I do know is my 12.7 HATES starting in the cold.
     
  6. jason6541

    jason6541 Heavy Load Member

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    Had a air compressor leak coolant and caused air compressor to lock up. After truck sat overnight in cold
     
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  7. 062

    062 Road Train Member

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    I would pull the exhaust manifold. That’s the best way I know of to know which hole and what’s causing it as far as fuel or coolant.
     
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  8. stonefly4

    stonefly4 Light Load Member

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    Oh yeah I'm adding coolant. I reckon that's a big clue. I don't notice any coolant leaking on the ground, so it must be going out the exhaust. My oil looks fine, (knock on wood) so the coolant is not going into the crankcase. (so far)

    I gotta fix this, or take care of it temporarily, somehow. I heard about Blue Devil. Don't know if I wanna go that route.

    The thing is, I'm willing to do the work necessary to install a new head gasket, but you know the old story—low on dough—get enough in the bank so I don't have to worry too much about taking my only source of income apart into pieces. It's almost a coin toss—take a chance on a much worse condition developing or take a chance on opening an ugly can of worms (unforseen complications of taking apart an otherwise good running motor.)

    The problem is getting worse, although slowly. It used to need to get down into the low 20s or teens for it to happen. Last week I shut it off at night and the problem was there in the morning, and it had only dropped to around 30 degrees.

    "Leaky injector cups" Yes, somebody else mentioned that. The temperature connection ought to be a clue. Would low temperature be more likely to affect a head gasket leak, or an injector cup leak?

    Last night it dipped into low temperatures (I'm in that snowstorm in northeast Ohio). I left the engine idling all night, which is something I don't usually do.

    Also, I'm running mostly water in the cooling system, with just a little antifreeze. I'll put cardboard against the radiator if I have to. I've got some experience with that. (Make sure you get the cardboard in place before things freeze. A frozen radiator core is a very difficult thing to thaw out in 0 degree temps.)
     
    Last edited: Dec 1, 2020
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  9. stonefly4

    stonefly4 Light Load Member

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    One good thing about this engine is that it always started in the cold, and I mean real cold, below 0 degrees Fahrenheit. This problem is that the engine won't spin. It's hydro-locking,or so it seems to be. As soon as it gets past the lock-up, it starts.
     
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  10. jamespmack

    jamespmack Road Train Member

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    Dear god, just fix it. Its gonna cost you more the longer you wait. Get antifreeze in it right now or your gonna have a junk block.

    Your gonna find a low liner or cracked head. If not block. Find the money to fix it right now or you will be out of business. Times get tough, you need to get creative. We all have been through it.

    Take care of a truck, it will take care of you!
     
  11. stonefly4

    stonefly4 Light Load Member

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    That could definitely be something very similar to what I'm experiencing.

    HEY!

    You just made me realize!

    It might not be the engine itself that is hydro-locking. Maybe it's the air compressor.

    Thanks! I need to explore that possibility.
     
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