New 450SEL project.. Need some K-jet help from the pros - PeachParts Mercedes-Benz Forum

mabbonizio · #1 05-21-2017, 10:07 PM

Hi folks,

I just picked up a pretty mint 77 450SEL off CL.Car was owned originally by a doctor who passed away where it was left to languish (presumably in doors).It does not run but I purchased it because it has mint paint, no rust, and 100k miles. The original Mercedes service booklet is even stamped with oil changes up to 90k miles from the local Mercedes dealer. I bought the car from a guy who bought the car from the original owner. He cleaned out the tank, replaced the in tank screen, filter, and pump. Still couldn't get it to start.

Yesterday I flushed all the injectors and got it to start and run briefly. Then it began bogging down and eventually died. At no point could I operate the throttle pedal. Today I found that lots of clean fresh fuel was entering the distributor but none was actually making it out of it. The line to the tank is clear.

Figured i'd pull the fuel distributor and take a stab at carefully rebuilding it. upon installing it back in the car and trying to restart, the distributor sent so much fuel to the first four cylinders that it actually hydrolocked the engine

I stupidly thought the battery was dying and tried to start the engine about 3 or 4 times before I thought it might be locked up.

I then pulled the plugs and let it blow the excess fuel out of the cylinders. After that I pulled the number one injector and the number 5 injector to compare them (kept them attached to the distributor and fed them into bottles). As I suspected the number 1 injector (and presumably 2, 3, and 4) was spraying more than double the amount of fuel as number 5. So I can conclude that I believe my issues are with the fuel distributor, it appears to be sending an unequal amount of fuel to different cylinders.

I'm wondering if anyone has successfully rebuilt this thing themselves (I've read about 5 different DIYS) or if anyone has sent theirs out for rebuilding with good results. Also hoping no rods were bent when the motor locked up

.. thinking maybe not since it was just the power of the starter turning the engine?

Whew.. apologies if that makes no sense I think I've inhaled too many fuel vapors today.

thoughts..?

meltedpanda · #2 05-22-2017, 02:24 PM

I would not be so quick to assume fuel distributor, the most important thing is to realize everything in the Kjet system is related, it never works to take a shotgun approach. You need to measure pressures. And I would replace the injectors unless you know they are good ( pop tested) Sounds like you have found quite a car, pictures please !
PM me your email and I will send you some info on the Kjet ,that will help with diagnosis and repair

mabbonizio · #3 05-22-2017, 07:11 PM

Quote:

Originally Posted by meltedpanda

I would not be so quick to assume fuel distributor, the most important thing is to realize everything in the Kjet system is related, it never works to take a shotgun approach. You need to measure pressures. And I would replace the injectors unless you know they are good ( pop tested) Sounds like you have found quite a car, pictures please !
PM me your email and I will send you some info on the Kjet ,that will help with diagnosis and repair

Hmm.. I can test the pressure coming from the pump.

Regardless I'll need to rebuild the distributor as it leaks ALOT now at the seam.

Pic of the beast:

aluminum · #4 05-22-2017, 09:18 PM

You might just swap out the unit and save time and money
Get one from salvage with a guarantee

I would Pull all the injectors and have them cleaned and tested . You well need all new seals and Lines related

andyslc · #5 05-30-2017, 06:51 AM

Got similar problems on my 75 280 SLC and decided enough is enough so I'm going to replace the injection with 3 SU 2 inch and manifold.
I can play with those as I got used to them on my old XK150.

mabbonizio · #6 05-31-2017, 06:36 AM

Just to update this thread, I replaced the fuel distributor with a rebuilt unit and the car now runs pretty well.

alabbasi · #7 06-04-2017, 11:26 PM

Quote:

Originally Posted by andyslc

Got similar problems on my 75 280 SLC and decided enough is enough so I'm going to replace the injection with 3 SU 2 inch and manifold.
I can play with those as I got used to them on my old XK150.

What?

meltedpanda · #8 06-05-2017, 03:46 PM

um ..... no

andyslc · #9 06-06-2017, 09:14 AM

I don't have any worries about replacing the K with carbs as I don't care about top speed, O to 60 time or mpg.
With a set of SU carbs I can balance them, adjust the mixture and set the whole system myself.
The K system is old outdated and not woth the hassle when things go wrong.

Diseasel300 · #10 06-06-2017, 10:12 AM

Quote:

Originally Posted by andyslc

The K system is old outdated and not woth the hassle when things go wrong.

Right, because Carburetors were invented this morning with the latest technology! Oh wait...

meltedpanda · #11 06-06-2017, 09:20 PM

so you have done this , can I see a picture, can you post a how to ?

Frank Reiner · #12 06-06-2017, 10:01 PM

Quote:

Originally Posted by andyslc

I don't have any worries about replacing the K with carbs as I don't care about top speed, O to 60 time or mpg.
With a set of SU carbs I can balance them, adjust the mixture and set the whole system myself.
The K system is old outdated and not woth the hassle when things go wrong.

andy:

If you feel that you must abandon the Kjet, skip that idea that you had about putting a carb on the Kjet plenum; get an original M110 carb manifold.
See pic.

andyslc · #13 06-08-2017, 09:25 AM

I started another thread on KJ with a photo of the manifold I will get made for 2× 2" SU's.
Not expensive to do in Thailand.