Pressurizing fuel, hard starting, dirty fuel/tank, bleeding air, new fuel pump

[Michael]

Many thanks for the further advice on this thread which, I think perhaps correctly, is focussing on the glow plugs.

Here is an update.

The hard starting problem has not been solved despite the previously described changes and the following (many of which were probably not necessary):
- replacing the existing (OEM?) Cole Hersee 12 volt continuous duty preheat solenoid (Cole Hersee part #24059 available from NAPA)[NOTE - THIS PART NUMBER MAY BE WRONG!  See Steve E. Delange's warnings to this effect at http://c34.org/bbs/index.php?topic=3347.45 from posts 41 to 46.]
- replacing the 10 amp circuit breaker that is in the electric lift fuel pump circuit (attached to the bracket that is attached to one of the energizing terminals of the preheat solenoid)(this circuit breaker is also a Cole Hersee product available from NAPA - part number 30056-10 I think)
- replacing the electrical fuel pump (as previously described,I think)
- cleaning all terminals and connections in the glow plug and fuel lift pump electrical circuits
- pulling and checking that each of the four glow plugs actually glows when individually wired across the battery terminals
- warming the engine and air intake with a paint stripper
- cleaning the air cleaner/silencer filter element
- re-pressurizing the fuel tank (as previously described)
- tightening and check for leaks along the fuel supply line (there had been a bit of leaking at the intake of the new fuel pump)
- checking that the solid electrical leads between the glow plugs were conducting electricity
- checking (and in one case wrapping with new insulation) that the solid electrical leads between the glow plugs were not shorting to the grounded engine block
- wiring heavy solid copper wire between the glow plugs (insulated except where it connects to the glow plug terminals) in addition to the existing solid metal connectors between the glow plugs in order to provide a temporary (better) electrical path between the glow plugs

Given that the engine starts well (first time every time) once it has been thoroughly warmed up, my attention began to focus on the possibility - to which Ron Hill averted - that the glow plugs are not working.

Peculiarly, even though the glow plugs seemed to work well (glowing very hot after about 10 seconds) individually when removed from the engine and tested when wired across the battery terminal, they produced no (or almost no) perceptible increase in heat in their vicinity in the engine block when apparently energized in place.  This unsatisfactory result occurrred both when holding the keyswitch in the "glowplugs on" position and when testing the glow plugs by making a jumper connection from the positive terminal of the starting battery right to the most aft glow plug (both when the glow plugs were connected only by their OEM solid electrical leads, and when also connected by the additional new solid copper leads, to the other glow plugs).

As mentioned above, there was no (or almost no) perceptible increase in heat after such apparent energizing of the glow plugs.  I say "almost no perceptible increase" because there might have been some slight increase in heat in the area of the most aft and the second most aft glow plugs...but that could just be imagination at work.

The upshot is that the glow plugs individually seem to work when pulled for inspection and testing but do not seem to work collectively when in place.  And it seems this problem is not related (or, at any rate, not necessarily related) to any part of the glow plug electrical circuit except as exists from a directly wired positive terminal of the battery to the first glow plug through to the last glow plug and return through the grounded engine block to the negative terminal of the battery.

Might there be a short circuit in one of the glow plugs such that, when that glow plug is installed in the engine block but not when it was tested as I did across the battery terminals, it shorts out the preheat circuit?

As best I can tell - please don't take this as gospel as their markings are a bit indistinct - these glow plugs are NGK Y103V glow plugs.  At a NGK website, these glow plugs are described as fast activated sheathed glow plugs that should be operated for 15-17 seconds, which corresponds well with Stu Jackson's recommended energizing time.

When the glow plugs were pulled, they were all clean except for the most aft glow plug, which was quite heavily covered in what looked like stringy carbonization. (I have no idea if that is what carbonization would look like.)

I would add, although I think it probably irrelevant to the glow plugs issue (but possibly indicative of the existence of another or piggy-backing gremlin) that the new fuel pump rarely if ever (I am not sure which) operates.

As ever, I would be heartened by any comments that this posting might generate.  I am back to the boat tonight for another round with these gremlins.

[Ron Hill]

Michael : On the fuel pump issue not operating all of the time here's what I'd do.  Run a separate #14/16 gage wire from the key switch "on" terminal direct to the + on the fuel pump.
Let me dig out Bill Nuttalls' Email address and have him send you a note on your problem.  He's got a C34, was a tech Ed a few years back and knows the M35 wiring much better than I do. 
If the engine will restart easily after it's warm; I'm most certain that the cold hard starting is a glow plug problem.   

[Michael]

Ron, as ever, thanks for the prompt feedback.

I'll run the direct connection from keyswitch "on" to + on fuel pump as you suggest.  Email from Bill Nuttall would be most welcome.

With respect to the glow plugs, I spent the evening trying to make them work in the engine block.  There was still no perceptible heat generated. And this was so when the glowplugs (directly wired to the battery) were "energized" (?) with all four in series or some in series or only one at a time.  This seems to shoot my theory that there might be one glow plug grounded out that was queering the lot.

It still seems odd that the individual glow plugs would apparently work - certainly get very hot - when bench tested but apparently not work when in the engine.

Mindful of Stu Jackson's comment about being wary of the negative side of the circuit, I did some of these tests with a second ground wire run from the negative post on the battery to another grounding spot on the engine block (starboard bracket bolt on the preheat solenoid - which on Hali is used as a grounding terminal for - I think the wiring diagram says -the tachometer and, now, also as the ground connection on the new fuel pump).  

Does anyone know how perceptible the heat is near a glow plug on the engine block when the glow plug has been energized?  I can't say I felt any difference in the temperature of the block anywhere near any of the glowplugs at any time...(although I might have imagined a bit of a difference occasionally).

My current plan is to install four new glow plugs on Monday, much as I hate throwing hardware at a problem that a better detective would solve by thinking.

Incidentally, there was a "my golly" moment recently when we cranked the engine with the front panel off...and for the first time could see that the V-belt was loose.  Had the starter been slow-cranking the engine so it couldn't achieve ignition?  Apparently not, because tightening the belt made starting no easier.  The engine still starts only after many, many crankings.

Anyone following this thread might also be interested in Mike Stimmler's somewhat similar hard starting problems and the solution he found - new glow plugs. See http://c34.org/bbs/index.php?topic=3347.0.

Finally, I should have mentioned in the list of things done that I replaced the starter battery to make sure there was no issue there...and because the old one might have been fading a bit in its war with the gremlins.  Unfortunately, the new battery didn't make starting any easier.

Cheers.

Postscript:  The problems identified in this thread - and the solution reached - are more thoroughly explored at Hard Starting/ Possible glow plug problem?? M35 Engines & Fuel Pump Wiring at http://c34.org/bbs/index.php/topic,3347.0.html.

The M35 engines are wired differently: the fuel pump only goes on with the key switch on glow plugs or when the engine is running and the oil ptressure sensor closes the parallel circuit to the fuel pump.  This creates unforeseen consequences to bleeding the engine, which requires either a fuel pump bypass wiring setup or holding the glow plugs ON when bleeding!!!  Read the full story at the link provided above.  [Stu  9/3/2009]