thanks for the FSM page toomany i appreciate it. yup, these 240s have the super simple manual system- engine,water pump, radiator,heater core controlled by manual knob in center console, back to engine, done

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

Not high on the list but take the effort and time to make sure there is adaquate fuel pressure in the base of the injection pump. In doing this you are actually restoring the system to good operational condition.

There are many side benifits I believe in doing so. I would shoot for 19 pounds pressure. Very low pressure is not a desirable situation on a 616 engine type. They will run with it but not as good.

Plus it then is only a matter of time until it lets you down once really substandard. This may be the most neglected area of getting 616 engines into their best operational profile.

Not costly either just takes a little time. Some will also still be okay. There is just no real way to tell where they are at pressure wise without going over them. I consider it an important part of a thorough tuneup and maintenance. These systems are getting really old now remember.

I also strongly suspect operation with ultra low fuel supply pressure will ultimatly finish the first cylinders rod bearing as well on the 616 engines over time. This suspicion is certainly not totally proven. Still there is adaquate information to indicate it as a potential cause to just ignore it.

That aside adaquate pressure will increase available power and increase fuel milage plus make the engine sound better at speed even perhaps. The permanent installation of a 0-30 pound ten dollar fluid dampened gauge in that circuit is a good ideal and a valid learning tool at the same time. Besides monitoring what is it should warn of impending failure of many things in the fuel supply circuit. At the very least the gauge will tell you when the fuel filters are becoming seriously obstructed and needing changed.

You can almost list the normal sources of road breakdowns on these engines. Fuel supply circuit has to be the number one issue. Followed by ruptured oil cooler hoses. Perhaps a fanbelt as well. It is always wise to pre empt a possible road breakdown.

The fuel pressure gauge goes a long way in this direction in my opinion. Combine it with a low oil pressure alarm and these engines start to approach the proverbial bulletproof status. Installing these two items is far cheaper that dealing with either of the consequences possible of not having them. Yet people really do not understand this yet in my opinion.

Also one last thing. Road reliability is improved by adding a little more heavy oil in the constant velocity joints. Or pulling the axels and totally changing the lubricant in those boots. The constant velocity joint boots have to be in good leakproof condition of course before doing this. Adding some more lubricant with sound boots is much easier and is far better than doing nothing.

Another slight advantage is the oil pump is directly mechanically driven on the 616s. Two many 617 or five cylinders still have the original oil pump chain that has never been checked since new for wear and tear. Most their oil pump chain failures do not land up well. Owners of suspected high milage examples of 617s should really check their oil pump drive chain. There is no comparison to what it takes in dealing with a failed chain later.

nice, thanks for all the info barry. i like dreaming of the the proverbial bullet proof status...! even more, i just want less chance of roadside breakdown

I'm game for testing the IP pressure and adding a fuel pressure gauge - any recommendations on a specific gauge? and where do i plumb it in? is the testing procedure basically adding a gauge and if pressure is off, then go from there? one of my 240s has significantly less power than the other, so im especially interested in getting that one a little peppier. 0-60 in 2 min never helps when merging on the los angeles freeway system!

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

There is a thread started by cervan in the archives called the relief valve spring. It is long and tedious but every 616 engine owner should read it. A lot was subjective back then but many things did pan out as to acuracy eventually.

My long research for example into the failing first rod issue on the 616 eventually became fact in my opinion. It aparently is almost unknown with the european examples of the 616 and the only fundemental difference is they use a different injection pump.

It was too long a time between a member once asking me why it always seemed the number one rod bearing failed at an unbelievable higher frequency rate on the 616 than any other rod.

The reasons given and in generally believed to be true at that time turned out to be in error. Some of them may have made a slight contribution to the overall problem. Just not enough to account for the failures. They did not make sense at all in fact in so many ways.

On your noticeably slower 616 check the linkage to the injection pump. It has to touch the stop for the pump arm with someone in the car pressing the pedal to the medal. Also check out the linkage on the one you find faster already.

I have little doubt there are literly hundreds of 616s and 617s driving around with limited responding throttle linkages. Even though they are so easy to check for function,

The fluid dampened gauge is sold by harbour freight and is of reasonable quality for a gauge of chinese manufacture. The 0-30 pound gauge has to be of the fluid dampened type.

The feed source to it is anywhere between the large fuel filter and the injection pump fuel input fitting. If the gauge indicates low operational pressure it is easy usually to chase down the culprit or culprits.

I am almost to the point of recommending for many reasons that people with 616 engines and no fuel pressure gauge at least put the stronger 617 lift pump spring in their lift pumps.

The present 616 lift pump spring was an error of some magnatude for the north american market I feel. It makes a major contribution to low pressure in the injection pump far more possible with poorly maintained cars. This primarily because any restriction in the secondary fuel filter is in effect magnified as the lift pump on the 616 puts out lower pressure than the 617 lift pump.

With low enough operational fuel pressure in the injection pump base over an extended time kiss the rod bearing on the number one cylinder goodbye. Not changing fuel filters often enough lowers the running pressure that is already lower with the weaker 616 lift pump spring.

Once there is no longer enough pressure to keep the relief valve open just insures more abuse. The undampened high energy spikes generated in the injection pump come into play by containing them. Relief valve open they are moderated somewhat by the cigar hose.

ok thanks, i'll check on the linkage, i was just reading another post about 240 linkage...
i found a couple different gauges on the HF website- not sure which one is correct- is it a type that plumbs in under the hood, or a dash gauge that has a sender?
i found these:
200 PSI Filled Gauge

2" LED Lit Oil Pressure Gauge

Mini Triple Gauge Set

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

also found one like this on ebay, maybe more what you are talking about?
New Hydraulic Liquid Filled Pressure Gauge 0-30 PSI | eBay

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

Range has to be 0-30 lbs. They may or may not catalogue them. This is a 10.00 fluid filled gauge that at least a few American members have purchased. I aquired mine at a Canadian outlet simular to harbout freight but called princess auto. We have no harbour freight outlets here.

The gauges are available in other places as well. Plumbing it into the cabin is your best bet. Otherwise there is no way practical to read the pressure at say 60 mph under load. If the working pressure under load is below the opening pressure of the relief valve on the injection pump. The injection pump elements do not all recieve the same amount of fuel at the right time. So the timing of the engine overall is changed progressivly from the number one cylinder down the line.

This results in the first cylinder being the one working the hardest with the second cylinder working a little less and the third and fourth cylinders progressivly even a further smaller amount less.

Over many many thousands of miles this additional loading wear takes the number one rod bearing out. It is my belief that elevating the pressure a little more than the factory recomended pressure of about 14 pounds pressure to 19 pounds . Not only distributes the cylinder loading better by putting all cylinders back on the same timing basis. It may even slightly be benificial in swinging the engine loading slightly towards the back of the engine.

It does no harm even if not so. You get to enjoy a better sounding engine and a more powerful one though if nothing else. Better fuel milage is a given as well. Even if not really very noticeable. A power balanced engine is going to be a more efficient engine. I no longer have any doubts remaining in this area at all and have passed on to other things.

For any member that has followed this area for quite some time. The lack of a cigar hose on the european injection pumps output to me has more signifigance than I personally want to examine. I think in one post that I responded to was adaquate proof that it is not only to supress noise as was thought but pretty vital as well for another function.

I am not going to jump into examining how they are dealing with certain issues with the european injection pump setup without them. I value what limited sanity I have left too much.

ok, so to plumb it into the cabin i would need to tap into the output from the spin on filter (a brass Tee) and run a hose from that Tee into the cabin and put the gauge at the end of the hose? i am assuming this is not a gauge that has an electrical sender, just a 1/4 MPT port that gets screwed into like:

New Hydraulic Liquid Filled Pressure Gauge 0-30 PSI | eBay

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

Thats the right gauge. The bubble is not so intrusive once the gauge is vertical. Your installation ideals sound good. Positioning this gauge in the cab is an unresolved issue to me.Waiting for someones better ideal. I currently favour in the glove compartment as it does not always have to be constantly visable. One member has his on the steering columb.