A little over a year ago I tried HPR diesel which is similar to biodiesel but is processed and refined differently. HPR has very poor viscosity and it was leaking out of my pump so badly that there were puddles of it under my car. I stopped using HPR and went back to D2 without any leaking issues for several months. I started getting leaks with D2 and tried running 10% biodiesel which stopped the leaking. Unfortunately biodiesel is no longer being sold in my area, so I was looking for an additive that would aid with lubricity of D2.

I bought a 14oz.bottle of BioBor on Ebay for $14.00 and so far 1oz. for every 10 gallons is doing the trick. The only explanation I can think of is that fuel with better viscosity passes through the system without getting hung up on worn out o-rings and washers. I replaced the crush washers between the barrels and the pump as well as the washers at the various tube fittings. I think that the o-rings that hug the barrels are on wearing out but that would require a shop to change out and I can't afford that. I hope that this additive keeps working for a while.

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'81 300SD

Some info is missing. Do you have a M type Fuel Injection Pump or an MW Fuel Injecion Pump?

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84 300D, 82 Volvo 244Gl Diesel

I don't know what type of pump is on a '81 300SD. I'd post a pic but the attachment option isn't working for me.

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'81 300SD

In the pic is an MW type Fuel Injection Pump.

If this is the Fuel Injection Pump you have where was it leaking from?

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84 300D, 82 Volvo 244Gl Diesel

There was fuel weeping from underneath two or three of the shims and it would collect at the 17mm banjo bolt fitting and drip down onto the lift pump.

Unfotunately you need to remove the individual elements in order to change the O-rings.

If you remove the elements to change the O-rings it changes the amount of fuel the element puts out unless you stick them back into the same hole in exactly the same position with exactly the same shim pack under them.

The Shim pack adusts the element's timing/begin of injection to the fuel injection pump camshaft.

I have only read of 2 others having the leak in that area. It is amazing more of us don't have leaks in the same area as you have.

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84 300D, 82 Volvo 244Gl Diesel

You are and have been a wealth of information on our old inline injection pumps over the years. A real asset to this forum.

You always gave me at least things to consider as well when you post your wisdom. A kind of one thing leads to another.

All I know for certain is that you have increased my knowledge of things I just suspected over the years. They say a little knowledge is dangerous but with these pumps perhaps still better than none at my amateur level. I also know you have worked professionally on these pumps at one time and wonder if all that skill, knowledge and experience background is known of and appreciated by all our members.

I will pm you one of my stupid questions as I have wondered for years if something is possible.

I never saw a MW Fuel Injection Pump with I worked in Fuel Injection. I am just able to piece the odds and ends of info I get on the forums.

My Father went to mechanics trade school but did not work as a mechanic. He fixed his own car and I had to assist.
More important I read his trade school books which were simple and well written.
Later I went to trade school myself taking diesel mechanics and they had a lot of info on how diesel fuel systems work.

And it is the fuel system is actually what causes most of the problems on Diesel Engines.

Working in the Fuel Injection shop I got to see the results of diesel fuel system issues and fix them.

So I ended up with a good mix of training and experience on Diesel Engines and Fuel Injection Systems.
After that I got a job at the Naval Shipyard where they rebuilt Engines and even the components like Water Pumps but no more fuel injection stuff.

Just like some people are good playing baseball because the have some talent for it I had some talent for learning the mechanical stuff. But, I had to work at it.

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84 300D, 82 Volvo 244Gl Diesel

Which version of biobor are you using? I have the same leak and still do not have the skill/confidence to remove the IP.

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Marc-André

W115 1975 300D "Geraldine"
W115 1976 300D parts/tutorial car

Yes, you described that procedure very well back in December. I went to the only shop in my area that works on Bosch pumps and he didn't seem interested in hearing me pass along the information that you told me. He said that it would require opening everything up and removing the rack. I got the sense that he really didn't want to bother with it and was just trying to scare me away with a high estimate.

Back to the main topic of this thread; any idea how 1 oz. of BioBor for every 10 gallons of D2 is keeping this IP from leaking? I'm kind of astounded.

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'81 300SD

2 Bottles Biobor BB16EZ01US 2 Biobor JF Diesel Biocide 160Z Each | eBay

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'81 300SD

Shops don't like to do patch up jobs on things because the customer is going to blame the shop if it does not work out and expect the shop warrant the job.

Some fuel injection shops won't put your used pump on their calibration machine to check or re-set the calibration. They don't want any of what is inside of a used Pump getting into their calibration fluid and the same with the oil/gunk that is inside of your fuel injection pump.

I only pulled one element body out of my spare MW Fuel Injection Pump and when I tried to get the Plunger out it would not come out. So I have no idea how the Plunger comes out. But, if all you are doing is replacing the O-rings you don't need the plunger to come out.

The other thing about shops is the don't like to do something they were not trained to do.

So basically it is like this; if your MW Pump is leaking from the element O-rings you can change them yourself (find some instructions on doing that) and hope but not expect it to come out OK. If you do that and it does not work out you have lost the cost of the Fuel Injection Pump Gasket Kit and some of your time.
If it does not work out you could get a used Fuel Injection Pump.

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84 300D, 82 Volvo 244Gl Diesel

I don't think it can. Probably coincidental.

You said earlier:
"I replaced the crush washers between the barrels and the pump as well as the washers at the various tube fittings."

My thoughts are something did not go right doing that work.

You also said:
"There was fuel weeping from underneath two or three of the shims and it would collect at the 17mm banjo bolt fitting and drip down onto the lift pump."

What shims? There are no shims that I am aware of.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

There's a flat black plate of some sort underneath the piece of metal held down by the two bolts, maybe it's not a shim but that's where fuel was coming from. Replacing the various crush washers helped the leak subside, but did not eliminate it.

I started running 1 gallon of biodiesel to every 10 gallons of D2 and the leak stopped. I continued filling the tank with this mix for several months with no leaks. When I stopped putting in a gallon of biodiesel when filling up with D2, the pump started leaking on the first fill up of 100% D2. I then tried BioBor and the leak went away. I'll try a fill up without BioBor and see what happens.

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'81 300SD

In the thumbnail pic of a MW Pump Element body you need to determine if the leak is coming form the area the Pink Arrow points to or the Area of the Spacer and O-ring.

If it is leaking below the 2 flanges that are on the Element Body then it is likely the Spacer is a sheet metal stamping that can rust through and/or of course the O-ring below it can simply shrink and get hard.

The orange lines are where the shims would go.

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84 300D, 82 Volvo 244Gl Diesel