Excuse my ignorance here, I’m still learning about the idiosyncrasies of diesels.

What would cause a diesel engine (1984 300D, ~200,000 miles) to be significantly harder to start when warm than when it is cool? It takes a good 5-8 seconds of cranking to get it fired up well enough to keep running when it is hot. (It takes only about 2-3 seconds of cranking in the morning.)

Compression is good, injectors are *new*, IP timing is O.K. I have seen some mention of ‘delivery valve’ seals, and this seems like it may be applicable to this situation – however, I can’t find anything on the service CD about the replacement of those seals. Could someone please point me in the right direction? Or am I even barking up the right tree?

Much Appreciated

RTH

If compression is good and valves are adjusted properly, the only thing remaining is a fuel delivery problem.

Changed fuel filters recently? How about fuel hoses? I had problems with the fuel hoses before and after the secondary (small clear plastic) fuel filter, but the symptoms were exactly the opposite of yours.

I'm interested to hear the causes of this too; keep us posted!

- Nathan

'83 240D "Steiner"
'00 New Beetle TDI

Not to imply that you don't know how to start it, but, the owners manual does say you need to apply partial throttle ( more when cold). My '89 Jetta sometimes requires pulling the cold start handle when starting hot. This will advance the injection timing when pulled out fully. I'm assuming that this is being accomplished by applying half or more throttle per the owners manual.

That's my two cents worth. Tell me if I'm full of it.

Rich

The only times I have experienced problems as you have described, the fuel delivery was being adversely affected by a clogged prefilter, and old fuel lines. I presumed the old fuel lines were leaking air into the system when they were hot, and sealed better when they were cold. Never did a post mortem on any of the hoses, but learned to replace them and the little plug on the number four cylinder injector at the first sign of any leakage. It is a two year (approximate) interval. The clogged prefilter was a recent experience, and the only time I have ever seen anything in that filter. I routinely (once a year and, depending on how the car is driven or quality of fuel used, possibly more frequently). The filter event was not a hot start problem, it was one of a series of problems that caused a "never start with the starter" problem, but "always starts by rolling and dropping the clutch in second gear" that I recently overcame and discussed here earlier.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

The only times I have experienced problems as you have described, the fuel delivery was being adversely affected by a clogged prefilter, and old fuel lines. I presumed the old fuel lines were leaking air into the system when they were hot, and sealed better when they were cold. Never did a post mortem on any of the hoses, but learned to replace them and the little plug on the number four cylinder injector at the first sign of any leakage. It is a two year (approximate) interval. The clogged prefilter was a recent experience, and the only time I have ever seen anything in that filter. I routinely (once a year and, depending on how the car is driven or quality of fuel used, possibly more frequently). The filter event was not a hot start problem, it was one of a series of problems that caused a "never start with the starter" problem, but "always starts by rolling and dropping the clutch in second gear" that I recently overcame and discussed here earlier.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)