A couple of my cars didn't start right away if I cranked right after the GP light extinguished, especially if the engine was a little warm and the light just flashes or doesn't come on. I usually found that turning on the key before belting in gives it enough time unless it's really cold out. I have replaced the GP relay, the (afterglow upgrade) one I installed in my '87 300TD was a new aftermarket and did this from new, ... I have also replaced GPs and never really found that this changed.

There is a coolant temperature sensor in the afterglow version (includes yours) and I believe (from memory) that all versions have a temp sensor in the GP relay box. In the non-afterglow version the sensor in the relay box controls the light only, not sure if the afterglow version uses this sensor for the light and the coolant sensor is only to prevent afterglow on a hot engine or if there is more to it.

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Gone to the dark side

- Jeff

Sometimes air is introduced because of a leaking primer pump. It may not leak fuel so you may not see any leaks, but it sucks in air as the fuel drains somewhere, and air enters the system...

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'82 300D (project)
'46 Willys (project)
"Nothing seems to be the way it should in this garage." -jt20
"Smarter than an engine, dumber than a hoodlatch..." -jt20
"Start jumping up and down to smoosh down those engine mounts" -DeliveryValve
"no" -kerry
"At this rate, you may have it done by winter" -layback40

The temperature sensor for the 602 glow plug is midway down closer to the front of the engine on the passenger side. I used to have the temp vs time graph but can't locate it basically at -20 the plugs glow for max time 30 seconds (?) and after glow is I think 90 sec. As the engine water jacket temp rises the glow time is reduced as is the after glow time.

If everything is operating corectly the glow light indicates pre glow time only. A flashing glow lamp indicates a short and if the glow light comes on after the engine has started then at least one plug is not working.

My 602 starts in under a second when cool, if its cold out -30 or more then I double glow it and it can crank a fair bit sometimes, a warm engine it starts in about a second and a half of cranking complete with a puf of black smoke.

Potential air leaks include all crush washers, hose clamps, fuel heater and fuel filter o-ring which in my observations will dramatically increase crank time if it starts at all.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

I think this is the normal symptom of air entering the suction side, unless the fuel level in the tank is above the leak.

If this is the case, try parking it ass-high with full fuel, and ass-low, see if it changes.

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Gone to the dark side

- Jeff

Thanks for all of the ideas - I will keep an eye on all of the above, and see if I come up with anything.

I just went out and started the car a few times. It seems like it turns over 4 or 5 times, and then starts. But once it starts, no hiccups, hesitation, or other signs of rough running. The thrid time, I timed it, and it only took 1.03 seconds to start up - so maybe it's all much ado about nothing.

A cold engine that is not initially getting the amount of fuel initially designed for. Will have a delayed startup. Air entering the system somewhere can do this while the engine is off.

My feeling is the first few sprays are just not enough fuel to light off on. So the engine just rolls over until there is enough fuel present to ignite.

That fuel supply system just has to be good and tight. At one time I used to pull a vacuum at the end of the fuel line by the fuel tank and see if it held on gas cars. Technically I believe it should hold on these diesels and may be the best test of the backflow preventing check valves in the lift pump.

Wear and build up deposits over time can make them less than perfect. I have not had occasion to do so but a check valve off an old Volkswagon or a new one as they should be cheap perhaps could be inserted in the hose down by the fuel tank.

They were located just ahead of the fuel tank on the old Volkswagon diesel cars. Perhaps the manufacturer did not trust the integrity of the system. I have removed them and found no change in the Volkswagons. They were suceptable to rock hits even though partially protected in their location.

Would a faulty OVP relay have any affect on crank times?

I started having intermittent issues with my tach cutting out, along with a loss of power and no response from the kickdown switch. Did my homework on the forums and found out that the OVP relay was probably the culprit - but the problem went away, so I stopped thinking about it for a while. Then yesterday, the car took dramatically longer to start - maybe 4-5 seconds, and requiring a bit of input from the gas pedal. Coincidentally (or not), the tach was inop again.

So a new OVP is in the works. Pretty sure it will fix my tach/power/low idle problem - any chance it will help with starting?

It CAN have an effect on starting to some extent. With the OVP inactive, your EDS solenoid will not be working, resulting in default idle somewhere around 450-500 RPM in park or neutral. You'd definitely notice the low idle.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)