Manager Forum

Have a customer who has one of these. The engine will not start under 45 degrees if it is not plugged in. Dealer looked at it and told him ONE cylinder is low on compression. 300 psi instead of 450. He asked me my opinion. Doesn't sit well with me, but I'm no diesel expert. What say you? Does this make sense?

Once it starts it runs fine. No other issues.

I would be checking the glow plug system. It only takes a couple bad ones to keep it from starting in cold weather. If the compression was low enough to cause a problem, it would show up on a cylinder contribution test.

I would check the glow plugs or the glow plug relay. I think the california emission one is different then the us built. They say compression on the dielsles are suppoesed to be within 20% of one another. SO there is not spec its 20% of each cylinder

I think if compression was that low it would miss

You could do a cranking amp draw test with the ign off and see if you have a week cylinder. To check compression on these, you have to remove the valve covers and take out the glow plugs. I bet that was never done....

got testing things 4 u to do. too much to type. left msg with your recptionist. you can post the fix if it works

Im pretty sure it glow plug issue they arent that hard to figure out. I would also look into the harness under valve covers the glow plug wiring runs through those and I replace alot of them.

liljoe wrote:I would be checking the glow plug system. It only takes a couple bad ones to keep it from starting in cold weather. If the compression was low enough to cause a problem, it would show up on a cylinder contribution test.

I agree. The dealership did get a contribution code during testing. Then they did a manual compression test. Charged my customer 600 clams and told him he needs a motor.

brianp87 wrote:I think if compression was that low it would miss

I agree. But it doesn't miss and otherwise runs great.

liljoe wrote:You could do a cranking amp draw test with the ign off and see if you have a week cylinder. To check compression on these, you have to remove the valve covers and take out the glow plugs. I bet that was never done....

The dealership invoice says they did. But who knows?

fortknoxx wrote:got testing things 4 u to do. too much to type. left msg with your recptionist. you can post the fix if it works

Thanks. Real busy here right now. I'll phone you tomorrow.

I would do a compression test. While v/c's are off check the harness connectors really good make sure they arent loose or melted. I would put in new glow plugs since old ones are out for comp test. then if possible keep over night and test in am when cold. Unless of course compression is bad(unlikely).

Bottom line is this, and I think we're in agreement, just ONE cylinder low will not likely cause this condition.

ric, i would go right for the glow plugs.


Glow Plug System - No Start/Hard Start Condition


TSB 04-25-4

12/27/04

HARD START OR NO START - 7.3L

FORD:
2000-2003 E-Series, Excursion, F-Super Duty



the newer dsls will start at temps above 50 degrees without glow plugs. they may smoke and chug a bit but will start. if there is a temp issue like the one your having it's got to be in the glow plugs or an outside shot a cranking issue. if the batteries are weak at all, and i mean even in the slightest it may cause an issue like this. the draw from the glow plugs may drain them down just enough to slow crank. another thing i've seen as the cooler temps close in is incorrect battery installs. i've already had two dsls come in with a hard start issue and found the issue to be battery related. one truck had two undersized batteries in it because the customer listened to a sales person, for lack of better words or profanity, at auto zone and purchased two 24 series batteries. the other had one replaced because as the customer put it "on was bad and the other so so" i only replace in pairs. good luck.

ricmorin wrote:Bottom line is this, and I think we're in agreement, just ONE cylinder low will not likely cause this condition.

+1

ricmorin wrote:

fortknoxx wrote:got testing things 4 u to do. too much to type. left msg with your recptionist. you can post the fix if it works

Thanks. Real busy here right now. I'll phone you tomorrow.

Turning Blue

Vehicle has not yet arrived. Might be here tomorrow as customer is not in a rush.

Youll figure it out. There not to bad really. I was scared the first time

Yeah. I've fixed plenty of these. The compression thing threw me. Didn't make sense. I'll post back when the jalopy gets here.

Ya I had one in that was missing and I tested compression. Couldnt find a spec it just said with in a certain % of each other. It ended being a bad injector(aftermarket) that the guy had installed somewhere else.