Early 250SL: No injection pump oil dipstick !?

[Benjegen]

Hi all,
I have just bought an early 250SL (May 1967) and it drives like a dream. When looking closely through the engine I found that there is no oil dipstick at the injection pump although there should be one according to the manual. Is it possible that this is a different type of pump which has no dipstick and gets its oil from the regular engine oil ? Or do I have to add into the opening capped with the "OEL" top ?
There seems to be a line from the engine which possibly carries oil, however I do not know definetely.

[A Dalton]

You have to look real close at the rear of the pump. Sometimes the 'T' handle has broken/lost and has been replaced with a cap, but it has to be there.
 The oil line you see if a feed for the oil seal only. The pump has its own oil res cavity/sump.
try a mirror...

[ja17]

Hello Ben,
Get the "R" number off the injection pump tag for a positive ID.

Joe Alexander
Blacklick, Ohio

[A Dalton]

As JA mentions , a pos ID will be the R#, but regardless of it being an early or late series [ R18, 18y, or 18z] res pump , you can be assured it has an oil res b/c of the OEL fill vent cap.. The force feed/crankcase pump that supercedes res pumps do not have OEL cap/vent. That is always the first thing to ID a res pumps at a glance. So, OEL cap equates to oil res... look at rear of pump for dip...some of them had a screw head dip vs a T handle one.
I think JA tour shows one....

[Benjegen]

Hi all,
thanks for the advice. I found the dipstick and unscrewed it. After that approximately 200 ml of oil came out. Was there too much oil in the pump I m a little afraid to start the car again, because I do not want to ruin the engine.
Thanks

Thomas

[A Dalton]

Way too much.
 I would drain it and start new ... Unfortunately, you have to suck it out from the same hole as the dip-stick . The easy way is to use a small tube and a vac pump [ I use a jar in between the tube and the pump that I made up years ago]. Refill with motor oil , starting with about 7-8 ounces and watch the dip stick. Refill is through the OEL cap.
 Then run it and watch the level.. if it starts to creep up on you , you have a seal problem in the pump.
 running with over dip level specs will interfere with the flyweights and resutt in a/f  mixture problems..
 Does the oil smell like gas??

[Benjegen]

Hi A,
Yes, I recognized a gas smell of the oil, so probably the seals are not Ok any more. I do not think that I can do that myself. Does anyone have an idea if this is an expensive repair ?
Do you think I can drive the car to the next service station ?
Thanks  
Thomas

[A Dalton]

You should give it a try
 You can use a squirt bottle to remove what is in there and then refill.
 About 250ml , if you have completely emptied the cavity.
I would not condemn the seals until I changed the oil and watched the level, as it may not have ever been done [ I have seen many where the owners were never even aware of the dip stick and fluid changing , even though they were diyer mechanics and owned the car for years...
 If you do not want to attempt it, then just get the level down to read on the dip correctly and drive it to someone you can trust and print this info out to show them, just in case it is new to them..it is not a hard thing to do/have done..but it should be done... it has prob been run like that for some time , so I would not fear any further damage , if there is any to begin with..
Let us know how you make out..

[Benjegen]

I will try to get out the old oil and refill it like you described (probably next weekend).
I will let you know about the outcome.
Thanks !

[A Dalton]

Here is another thread to help give you  little confidence.

 http://index.php?topic=2972+level+

 Print it out in case you have to have someone help you out with it.
 Also note that some do this change and everything comes out fine with no more problems .. it is a standard maintainance item, so at least you are aware of it for future  maint.
 My theory on these chassis is lube, grease, and  then grease again..
 and again....and ....

[J. Huber]

Well, I had put this project off long enough. Quick history -- can't remember last time I had this oil changed -- maybe never. When I had checked level it seemed high -- about an inch and a half over the notch. Today I used a windex pump and drained the FI pump. It was a little like milking a chocolate cow but I did it.

Here's what came out:


Download Attachment: FI Oil.jpg
36.01 KB

Holy cow. A bit more than 180ML I'd say. I refilled with 10/30 and thought I was being clever by measuring 180ML into the pyrex. Problem was I spilled half of it...so had to just keep filling until it showed on the stick. Now, to be clear, the notch on the dipstick is the correct level, right? Anyway, it is very hard to read since its so clear but I think I got it close. I will be monitoring this level closely.

James
63 230SL

[A Dalton]

JH

 The line is the correct fill on dip.
 It is hard to read the first couple of times , so just try in a couple of days , as it will darken up a bit and be easier to see... I always do it first thing after a nights sit.
 It is also more important to go by the reading vs pre-measured fill b/c you do not know if you got all the old out.  The actual fill with a completely dry sump is 250ml.

[Naj ✝︎]

AD,

Dipstick question:  

quote:The line is the correct fill on dip.

So, when is the level correct:
When you unscrew the dipstick and read or,
Take the dipstick out and wipe it clean, insert into pump (without screwing it in all the way and) then read it?

naj

65 230SL
68 280SL

[hands_aus]

quote:Originally posted by naj

AD,

Dipstick question:  

quote:The line is the correct fill on dip.

So, when is the level correct:
When you unscrew the dipstick and read or,
Take the dipstick out and wipe it clean, insert into pump (without screwing it in all the way and) then read it?

naj

65 230SL
68 280SL

Hey Naj,

Take it out, clean it , screw it all the way in and then take it out and re-read it.

At the moment I am running mine with the dip stick reading half way because the oil level increased above the full mark over a 12 month period. This affected the economy of the engine.

On a recent road trip the car returned 21 mpg (Imperial). I was delighted.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[hands_aus]

James and Benjegen,
With the correct oil level, the governor weights of the Inj Pump will spin more freely and not be spinning in thick sludge. Hence the air / fuel mixture might have to be adjusted.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[A Dalton]

quote:Originally posted by naj

AD,

Dipstick question:  

quote:The line is the correct fill on dip.

So, when is the level correct:
When you unscrew the dipstick and read or,
Take the dipstick out and wipe it clean, insert into pump (without screwing it in all the way and) then read it?

naj

65 230SL
68 280SL

N

 Screwed in for  correct reading.  That is why I mention that I do it in the morning after a sit. That way, you are sure all the oil has settled and you do not have to pull the dip, wipe it, and then rescrew it for measure. It is a real volume reading. It is also easier to read then as the oil is ambient temp, which means it is thicker than from a warm engine and the viscosity of the cold oil shows to the eye much better as you can actually see the bump of oil on the dip even if the new oil is perfectly clear.
 That is a good question and the answer pertains to all sorts of oil crankcase type engines . I have allways found the true reading for all of them [ even my lawmower] require full dip insertion [ or screwing in ] to result in correct readings.....

[Naj ✝︎]

Thanks AD for response with explanation.

 

quote:The line is the correct fill on dip.

naj

65 230SL
68 280SL

[Benjegen]

Hi all,
I changed the oil and it was a real mess. Approximately 450 ml of gas stinking oil came out. Subsequently I added new oil (approximately 220 ml until it was the max of the dipstick) and drove approximately 4 miles. Everything seems fine and the engine seems to run  better (more calm).
Thank you for your help.

Ben

[German Dude]

This thread made me check the oil level in my pump...

I am glad I read this before so I came prepared and did not spill too much oil. About 350ml of it came pouring out of the pump...

Well, looks like another oil dipstick has become part of my regular checks.

Thanks for the info. I said it before and will say it again: This site has been the greatest help since I got my red one.

Best,

Juergen
64 230SL #2933, 4sp, signal red, white hard top
93 Citroen XM station wagon

[A Dalton]

While we are here:
  There are two other things one can check on the same pump.
 The OEL fill cap is also the pumps vent and it has a filter inside the cap . This can be cleaned out w/kero.  The air intake for cold start mechanism also has a filter .. you want to check that. I have seen them plugged.

[enochbell]

A little off topic, but not really:

First, my sincere appreciation to Arthur for sending me an article that does a superb job of explaining the workings of the injection pump.  It is a fairly complete technical article written in layman's english.  I would be glad to return the favor and send it along to anyone interested in it.  I would offer to scan and post the article, but I assume it is copywrited and that would probably not be fair to the author.

Second, I have a bear of a time reading the dipstick on my pump.  The oil is about 6 months old, but it still does not give me a clean/trustworthy level to read (yes, my glasses are working!)  Has anyone come up with a way to enhance the contrast or some other trick to make reading clean oil on a silver background any easier?  I also find it impossible to insert, seat and withdraw the dipstick without rubbing it on the inside of the hole.

Thanks,

g

'64 230sl, fully sorted out...ooops, spoke too soon

[A Dalton]

Another trick I use..
  For a better visual comparision, draw a thick line down the dip stick with a black magic marker . Let it dry and then try it.  Once level is established, wipe the marker ink off w/lacquer thinner.....
[ or cheap hair spray]