I purchased a 1984 300D with 190,000 miles this month. Yesterday my father was driving the car in a hilly region and experienced serious slowdown from 50 mph to 20 mph going uphill with rpm going to 3000. When he stopped at a red light the car went dead. This happened twice it restarted after a few attempts.
This sounded like a fuel system problem ,from my limited knowledge my thought was to change both fuel filters. From the previous owners records this maintenance does need to be performed.

My father initially thought the transmission might be to fault. It does shift hard.
My questions is what is the problem? and what action should I take?

you are correct. change fuel filters (both)...

hard shifting is a vacuum problem - maybe leak, maybe adjustment

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Thanks Zeke. I am off to the parts store now. I will let you know how it goes.
The vacuum problem is next on my list. Thanks again for your help.

I second zeke. Fuel filters, and possibly a cleaning of the tank strainer if the problem persists.

The hard shifting is vac related. You might have leaks or if it's only slightly hard you might need to adjust the transmission modulator a touch. Troubleshoot vac leaks first.

__________________

Make sure you fill the secondary filter with a burnable liquid (diesel, purge, transmission fluid, canola oil, etc) when reinstalling or you will have to purge out a ton of air.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I towed the SD one time when it got slow & I didn't know about diesels & filters. 2 sets now stay in the trunk along with tools to change. It only takes a couple of minutes even if on the road side.

__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

It sounds like the car needs a good going over.
A couple of weekends. Filters are a must, check the strainer in the tank for black goo!!
Valve adjustment is probably overdue.
The trans probably needs a fluid & filter change.
Change the coolant as well.
You will probably discover a vac leak or 2 or bump a hose & cause another while you are doing all that, fix them.
Then take a deep breath & see how it goes.

Good Luck

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

I changed both filters and it is running great again. I am going to do exactly as you say layback40. I will have the next couple of weekends free and will get all of the maintenance up to date.

Along these lines I am looking for a DIY on fuel tank strainer replacemment.
I have an 85 300SD that sat for a while. I am about to change out all the filters
even though it runs okay ( needs valve adjustment) If the filters are not cruded
up (as some photos here have shown) should I even worry about the strainer ?
Alan

__________________
92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )

I don't think anyone mentioned (in addition to the above mantainance punch-list), a banjo bolt/ALDA cleaning.

__________________
1989 300E 144K

Fuel tank strainer aint nothing but a thing if you have a big enough socket. 36 mm?? , I forget the exact measurement. I ran the tank down, used my oil evac to get the rest out, and still caught maybe 1/2 gal in a drain pan under the tank.

Eyeball the rubber line and see if it needs replaced at the same time.

This was a '95, so YMMV!

WINGAS, I just ordered all new Viton hoses and will install soon. This includes
a Viton gasket seal for the strainer and all rubber involved with the tank.
I noticed you have a 67 Chevelle. I had one that I used to make some money on the street with as well as on the strips in MD/VA. I ran a .030 over 396/375 H.P. God I miss that car it was painted a Chevy 1962 (?) anniversary Gold with pearl in it and had a 6" snorkle scoop. Centerline wheels all around with ladder bars and damn that thing would hook up. I could pull the wheels up and jump a coke bottle without even trying too hard. Anyway that was back in the day
( 1976-1980) I had to sell it to pay for college and a friend bought it and promised to offer it back to me first crack when he sold it. Needless to say he did not contact me and he sold it. If I ever see him $53>/:****. Anyway keep
and enjoy.
Alan

__________________
92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )