Some weeks ago I wrote:

"My 244 Diesel with D24 engine has a cold start problem.

On summertime it is OK, but when the temperature goes below 0 degrees centigrade (32 degrees Fahrenheit), the engine is difficult to start. The glow system light on dashboard operates normally. After starting, a lot of gray smoke comes for a couple of minutes and the engine runs poorly. But when the engine warms up, everything is OK.

The glow plugs (Bosch Duratherm) were changed about 1 month ago and it started well for a couple of weeks, but now it is as it was before the glow plug change.

The glow system and cold start device are OK and the engine is in comparatively good condition.

Is it possible that the glow plugs are damaged or dirty after only 1 month of operation?

So what am I supposed to do next? What should I check and/or change? Does somebody have own experiences about this? "

Some good guesses came, like Jim Bowers wrote:

"As the temperature drops ALL the glow plugs have to be operating properly. They don't get dirty, they just burn out. Is the "glow time" correct? I had a couple progamer relays fail on me and the "glow time" got to be too short. The coolant sensor that tells the program relay how long to "glow" may need attention also. My shop manual had a chart of glow time versus coolant temperature. (I sold it after I sold the car so I can't check the information for you.) Also check all the connections at the glow plugs to make sure they were done correctly. Was the place that did the work for you "qualified"? Are you sure they changed them all, or did they just check them? They are tough to get to, especially the one behind the pump, but they have to be done right because each one draws about 12 Amps of current. I found the life of the plugs was highly variable and I only changed them when one failed.

Is the cold start device on the side of the pump moving that lever through a good 15 to 20 degrees from cold to hot? Mine degraded with time and needed to be replaced eventually."

and another one from Jim Baron:

"My experience is all with VWs, Mercedes, and Minneapolis-Moline, but since your Volvo is really a VW, is suggest the following:

Remember that if your injectors are not spraying a good fine pattern, they can cause the glow plugs to deteriorate very rapidly by shooting a steam of fuel right on the tip of the plug. So start by rechecking the glow plugs to establish whether the new ones have degraded rapidly (tips burned away), which could indicate an injector rather than a glow plug problem. The guys at a VW diesel parts site (www.bright.net/~vwdiesel/) recommend the following as a means of cleaning injectors, believe it or not: get a new fuel filter and before installing it, fill it with non-synthetic ATF so that the engine starts on ATF (rather than diesel #2), which is a very powerful cleaning agent, but will burn in diesels, provided that the air and the engine are not too cold.

The ATF quickly becomes diluted with incoming #2 diesel enough that the car can be driven normally but the injectors get a good cleaning by then.

On the other hand, is it possible that your climate region is such that your fuel source does not properly reformulate its fuel for the various seasons? Try buying some other brands, especially from the big truck pumps."

Unfortunately none of these assumpitons were correct. All the glow plugs were changed and are OK. I know, because I did it myself. The fuel and the fuel filter are OK. The injectors are not that worn either and the cold start device is working. So, what next?

Please, give more hints, even if you feel that your guess would be totally irrelevant. Own experiences, etc. Thanks already.

Teemu,

When I was having cold starting problems, the relay under the hood was in the process of failing. The engine would take 3 to maybe 10 seconds of cranking to get it to start (where normally all you had to do was just think about touching the starter after the glow sequence and it would purr like a kitten) and then would emit massive clouds of grayish smoke which would make all the birds up in our tree scatter. Your description of it being okay when warm may indicate the relay is failing. There are two sets of contact points inside the relay. I'm no expert, but they appear to both operate together. Mine had pitting and burned surface area which, when cold apparently had too much separation to make contact. When it was warmer, this was not as much of a problem and it started much more like normal. If you pull this relay and open it up. You can see the points and perhaps see the problem.

You will have to scrape the silicone-like material from the bottom of the unit to see how to get it apart, but it comes apart fairly easily. The recessed nut/bolt that you can see when looking at the bottom is NOT the way to open it--been there, done that, didn't work. Check this out, it may be your difficulty.

Post back when you find the cause, okay?

Credit goes to Abe Crombie for this bit of information, since he is the one who told me about it and is tons smarter than me, which actually doesn't give you a very good idea of just how smart he is. :-)

You say your injectors are not"that worn"... When I had the head off of my d24 after only about 100k miles

I brought all the injectors in to a fuel injection specialist for only an ispection,

and they told me all the injectors were bad and that

they would eventually ruin the engine. I was really pissed cause I thought they were stiffing me. In retrospect

I think they were right. They argued that in passenger cars injector life is much shorter than in big rigs, and

they should be routinely replaced every 70k miles to maximize engine life. They even showed me a new

injector vs the ones I brought in and a visible crater in the used injectors still didn't convince me at the time.

Fact is, the injectors do work alright, but I have the same cold start symptoms you describe and it is

getting progressively worse (yes, I just threw the old injectors back in!)

If I had a diesel that I wanted for as long as possible I would keep new injectors running in it. If your

car has been running awhile on working injectors with poor spray pattern it is very likely that you

are gradually loosing compression (particularly if the injectors have over 100k of service). D24 engines

are notorious for excessive cylinder bore wear. (There was alot of discussion about this on the

swedish bricks board in early 90's; some of this can still be found there under FAQ)

I decided to just run this damn thing until it dies, then convert it to gas. What I love about the D24

models is _they don't rust_ (I live in Maine)! I've got one converted, but it's still waiting for completion.

The other one I talked about above is still rattling.

Get out your multimeter and check for burned out glow plugs as a first check. Disconnect the electrical connection, copper buss bars, at the top of each plug and measure its resistance. You should measure about 1 ohm or less between the head and the plug's input terminal. Don't worry much about the actual value. My experience was that when they burnt out the resistance was way over several 1000 ohms.

I used to remove the vacuum pump to ease access to the connections. Just be careful of the "O" ring when putting it back. Also turn the engine so the plunger is in the engine and you don't have to compress the pump's return spring at the same time you are trying to manuver it back into position.

For the one behind the pump leave the copper buss connected to that one and make the measurement through the buss. (Isolated from the other plugs.)

I suppose a very first check would be to be sure voltage is getting to the buss at the same time as the lamp in the instrument panel is on.

Good luck and let us know what happens.