Rough idle after starting
 

Lately my CD runs a little rough for the first 30 seconds or so after a cold start up. It still starts easily and once it runs a few seconds it smooths right out. So, I'm pretty sure one (or two) of my GPs has probably died. Not that big of a deal since I have some good spares lying around.

My question: what is the quickest, easiest way to pinpoint which one? Any suggestions on how to do it other then disconnecting the wire and checking their resistance one at a time? The weather around here right now doesn't encourage spending much time outside working on cars (cold rain), so I'd really like to minimize the time spent on diagnosis and repair of this relatively minor issue.

You pull the plug at the relay and check resistance on each socket in the plug. If it takes you more than two minutes........you're doing something wrong.

That sounds great. Where is the relay located, and which socket matches up with which plug? Sorry, I don't have a manual...

You can put an Amp meter around each wire going to the GP's are see which one is lower than usual.

It's a black box about twice the size of a cigarette pack and should be on the left fenderwell. There will be a plug with five sockets inside. There are small numbers next to each socket signifying the cylinder number. Look carefully.

Another good idea - if I had one of those amp meters that you clamp around the wire...

The Diesel Giant site has a pictorial on how to check the Glow Plugs with a meter. When the page opens up you will need to scroll down the page some to see it.

If you do not have a Meter Harbor Freight sells digital Volt/Ohm/Multimeters for $3.

Also the Gloe Plug connector at the Relay has tiny littl numbers that tell you what Cylinder it goes to.

No problem there - I have 4 different meters I can use.
Thanks guys. With that info in hand it sounds like it should be a cinch to figure out which one is dead...

Jut a quick update for those who offered help and suggestions.

I measured all of the plugs at the connector and got 1.9-2 Ohms on all 5 - none burned out. I read in other threads that some people wait until 5-10 seconds after the GP light goes out before cranking, so I tried that and got better results - less stumbling and a smoother idle.

So I decided to try the next step up. I've been cycling the GPs twice lately - as soon as the GP light goes out I turn the ignition off and then immediately back on. Once the light goes out a second time, THEN I crank it over. Works like a charm. Idles normally right off the bat again.

We've been having overnight temps in the low to mid teens for the last couple of weeks so this must be just my CD's way of punishing me for making it sit outside in the cold insead of inside a warm garage somewhere ;)

Although all those plugs work, they're probably old as hell and are not providing the necessary tip temperature. If you can find a warm day, change all five. Remove the hardlines as a group to save yourself some misery.

Glow Plugs
 

We have been getting down in the twenties at night. My 83sd will kick a couple of times if I don't plug it in. So I plug it in. The car is MUCH happier to start when the coolant and block is hot. Don't fool with the glow plug light. That is just going to tell you when two or more plugs are bad. It will tell you that by not coming on at all. The time cycle for the plugs is about 30 seconds. I usually just watch the orange low fuel warning light and when it brightens, that means the plugs are no longer warming. So two cycles should be about a minute.

Hi Bob,
When I bench tested my glow plugs, the time it took for the tip to get red hot was about as long as the glow plug light stays on. The longer you let them glow, the hotter it gets in there and the easier it is for the car to run smooth. I let them glow until the relay kicks off, turn the key off and then start her up.

Hey, there's a nice CD in Tacoma right now for $1,000.00 :cool:

If you don't touch the key the glow plugs will stay on for quite some time after the light goes out, 45 seconds or so. You can hear the relay kick off. When it gets cold wait until the relay kicks off before you start the car or you can turn the key off and go another for another glow round. This will help a ton. The way you are doing it you are getting about 20sec of glow time, two 10 sec glows. It takes a glow plug several seconds to get up to temp, so you aren't getting the most out of your plugs. If you wait until the relay kicks off to start a second glow you are getting 45sec straight, plus whatever time you go the second round. Much warmer, and a much happier cold start.

Actually I replaced them right after I got the car - about 18 months or so ago...

The 20+ seconds I'm waiting now seems sufficient. Two glow plug "light cycles" and it fired off and ran smooth this morning at 13*. I'll keep the info on longer cycles and the length of the relay timer filed away for future reference.

I can always wait a little longer to crank it if 20 seconds isn't cuttin' it...

Where? On CL?

Now that's quite surprising............were they Bosch or Beru?

Injectors.

Bosch. Wish I could have found some Beru without waiting for someone to ship them.

Good thought, but I don't think that's it.
All mine were professionally cleaned, pop tested, and balanced by a local injector shop almost exactly a year ago.

I'd sure like you to pull one of them and put it in a vice and apply power.

This would, with certainty, tell us whether they are tired...........or whether they work perfectly fine and the engine is tired.

Well, since a 20 second glow is all it takes to get a smooth idle after starting, it starts on the first rev, gets 26 (+/-1) mpg in mixed (mostly city traffic) driving on winter-blend fuel, and doesn't smoke or use oil, I'd say its not likely that the engine is all that tired. I think its most likely just a case of temps in the low teens AND less than top notch (quality) glow plugs...

You may be right.

However, the SD starts instantly at 0°F. after a 15 second glow. It does use a touch of oil and it gets 29 mpg in mostly highway driving.

Its glow plugs, with the exception of #5, are much older than yours.

So, calling the plugs the culprit without a test might be a bit premature.

When I state the engine is "tired", the situation could be valves that are not completely seating properly. The SD was identical to yours prior to the replacement cylinder head. I'd struggle to start it at 12°F.

Had a temporary problem like this, adjusted the rack dampener and it starts strong now. It came to a point that starting the car in the morning led to stalling. Must have been over adjusted before.

No more fluctuation of RPMs too.

It could also be a worn pump, all other things being well maintained and compression not an issue, particularly if the rack dampener evens things out.

MAYBE IT'S A TUMOR!

Jeez you guys are a real bunch of doomsday pessimists!

I think its fine guys. If all it takes to start right up and run smoothly is a 20 second glow, I don't think its time to spend a few grand doing a complete rebuild of the engine, and the pump, and the injectors, and..., and..., and...

If anything it is a little overdue (12-13 thousand miles) for a valve adjustment.

But thanks for the tips on how to check the GPs quickly and easily.

Not at all.

My experience with the SD shows that these engines are a bit compromised in valve seating at 150K. The difference in performance with new valves is striking.

You may elect to avoid valves via extended use of the glow plugs...........or a complete change in glow plugs, but no 617 has valves that are not a bit compromised at 200K.

Well, given that they have to be adjusted every 10-15 thousand miles, I'd say that is definitely true. If they have worn (or stretched or whatever they do) enough to get tight and need to be adjusted 15-20 times by the 200k mark, they have to be at least somewhat "compromised".

HOWEVER, I don't think this engine has 200k on on - maybe not even 150k. You may recall I did an engine swap last fall, and this engine is definitely in better shape than the 200k one that it replaced - even before that one dropped a rod or two.

Like I said, my first step will be adjusting the valves since they are a bit overdue. Even if that doesn't fix the "problem" then I'll just have to live with 20 second glow cycles, because I'm not about to do even a head rebuild (much less an entire engine rebuild) on a motor that runs this well and this strong otherwise. IMHO it just wouldn't be worth it. It will take a lot more of a "problem" than that to justify the work and expense required.