Hi there folks, i am swaping a 87 300 sdl engine to be mounted in a 91 350 sdl, what should i be aware of ?, could the fuel pump regulator of the 350 be used w/o problems with the 300 engine? have anybody done before such a swaping?
Any comment will be much appreciate, thanks

Need help asap with some of the knowledge of you guys, i can`t changing the engine from the 300 to the 350 w/o knowing if it can be done and what kind of problems should i expect, thanks for your help.

Of course it can be done. Very easily, in fact. I think any issues you encounter will be very minor.

What do you mean by "fuel pump regulator"?

I have seen a thread about doing this conversion before. have a look in the othere parts of the forum.

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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.
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it should be a pretty straightforward swap, i dont forsee really any major issues, have at it.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Hi there, thanks for you answer, i mean by that the black box linked to the fuel pump, somebody told me that the 350 is suposed to turn at less rpm that the 300, i don`t know is that is true, but some of you do know for sure and is the knowledge i`m looking for, i don`t want to make mistakes, i`m gonna try to keep the 350 for the rest of my life w/o going broke and don`t want to begin messing up a good engine, any help will be appreciate, thanks.

Huh? I get the feeling there is no such thing... max rpm is something internal to the injection pump, and the 300 will come with it's own proper pump. It probably does something else. Maybe it's the vacuum control valve?

The turbo on the 3.5L (OM603.970) is slightly different than the 3.0 SDL engine (OM603.961) as it doesn't have the ARV, so the .961 turbo will be slightly longer, you might want the rubber boot from the '87 car. Better still is to keep the '91 turbo, it is a slightly larger turbine and should improve performance / allow slightly more fuel & power to be tuned in.

The injection pump (and thus the engine) on your replacement engine will allow IIRC 400rpm more, so you'll be able to rev higher, except the automatic shift-points won't allow it. The stall-speed of the torque-converter is also slightly different to accomodate the different power curves and RPM limits of the two engines, might slightly affect launch performance. Best IMO to install the replacement engine and transmission together so that they are matched, not a big deal though.

The '91 glow-plug system has "afterglow" where the glow-plugs are on with the engine started in some instances, the '87 engine's glow-plugs will not last long in this configuration, best to replace them with "afterglow rated" plugs for the '87 190D turbo. If you are installing the head from your '91 on the '87 engine, disregard, but you'll need the complete head with injectors, glow-plugs, and injector lines to do so (good swap).

The '91 engine's oil pan is matched to the '91 engine, but has a windage-tray in the pan, I prefer the '91 pan on the '87 engine if you so choose.

The '91 engine also has a stronger front-cover / timing-chain case, if you are getting in that deep you will need to pull the harmonic-balancer which allows you the opportunity to renew the timing chain & guides (or at least check), and the oil-pump and chain.

The max RPM is limited mechanically inside the Injection Pump, no changes necessary there. Even with the original '91 transmission you will be able to use the extra HP from the 3.0L engine by shifting manually and using the entire RPM range. The power curve IIRC continues to increase as the RPMS rise, meaning the higher the RPM the more power output up to the limit (not including the throttling range of the governor = some power loss at the top). Idle RPMs are electronically controlled as you apparently are aware, and the same for both engines.

All I can remember at the moment.

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Thanks Babymog, is wonderful to have some of you around in this forum, such knowledge is a great value for the whole comunity, the idea is actually to swap the whole 603.961 in the 350, i got a nice engine from the junkyard with all the peripherals included from a 87 300SDL who was running at the moment of going to the yard, unfortunatelly i din`t buy the transmission at that time, but actually you are making me think about using the stronger turbo of the 970 engine and of course the glow plugs, also the "head" in the 961 is the famous number 14, i have to check the one from the 91, are they compatible ? when yes i think i`ll beter replaced it this one too, i still have the disasembly 970 engine in the trunk of the 350 so i can swap anything necesary for a good conversion, i`ll try to get the best from both worlds as this car is suposed to be the car for the rest of my life if nothing serious happen to it, any other help or new ideas will be much appreciated, thanks.
PD: i do have another 87 300SDL that is making something who annoys me a lot, after you trap on the gas pedal there is some delay in the transmission to begin pushing the car, sometimes if you trap really hard on the pedal the car keeps in doubt for a second and them spring with a big jump, what can be the problem?,
the car do have 245.000 miles on it.

Yes the heads are compatible, but as mentioned, the newer head on your '91 engine has the "angled injection" so the injectors are different, pre-chambers different, injector lines are different, and the glow-plugs are different. Definately worth installing on the "new" engine.

Hard to decide where to draw the line on these things, while the engine is out and easily re-sealed etc., new valve seals and new front/rear seals aren't bad insurance, many more gaskets and seals that are much easier to access out of the car.

On the '87, search ALDA, sounds like a likely suspect.

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Gone to the dark side

- Jeff