A little 240D engine help, injection timing device - PeachParts Mercedes-Benz Forum

Stevo · #1 06-05-2002, 11:57 PM

I am looking for a little help with the removal of the fuel injection timing device SHAFT.(1980 240D manual) The Haynes manual says "push the shaft out through the rear of the housing" It wont Go, and I am a little reluctant to beat on it. The "helical" gear for driving the oil pump is still in place and I see no info for removing that. Could that be part of the problem? Needless to say I am a novice "wrench" but things have gone ok so far as I am really taking my time and hopefully will be able to get it all back together. Everything is apart except for removing this shaft which has me stumped so any help from you guys would be much appreciated. BTW I am doing an over haul, that is if they dont tell me that the 2 damaged rod journels are toasted beyond repair.
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tcane · #2 06-06-2002, 12:40 AM

The injection pump timing device shaft also turns the oil pump shaft. To remove the IPTD shaft you will have to remove the 27mm bolt located in the recess area on the block, a 13mm bolt on the side of the block (if your engine has this), remove a sleeve below the 27mm bolt using needle nose pliers, remove the shaft/helical gear, then the IPTD shaft should slide out.

Good Luck!
Tom

leathermang · #3 06-06-2002, 08:59 AM

If you have a digital camera I hope you will take lots of pictures of your overhaul... it would really help when the FAQ pages are being made... thanks, Greg

ps, I have the exact same car you do...

Stevo · #4 06-06-2002, 11:50 AM

Tom
Thanks for that. With your help and a little head scratching its out. I will tell you guys I would have never attempted this project had I not found this group. Of course theres allot left to be done but the getting started part is well underway.

Leatherman

I do have a didgital camera and will take some shots but for anyone doing this for the first time like myself this timing device thing has been the only part so far that has not been straight forward if you have the manual. A knowledgeable MB friend showed me a few things about about the head. I was just going to send it "in" but he insisted its "no big deal" so at this point in time he showed me how to pull the valves and seals out, check the slop in the guides, label the valves so they go back in the right holes. Today I will get the head cleaned up (bead blasted?) and magnafluxed. We will then determine what needs to be done next. I would think the valve guides would be replaced as they are cheap but I dont know about those roto gizmos. I will post the progress as the fun continues. Actually it is allot more fun than I thought it would be as these engines are a marvel of engineering and its really cool to check out each part as you take it off. I am cleaning things up in kerosine and storing them in zip lock bags so when its time to reassemble I wont get too screwed up, I hope. Oh ya I borrowed one of those engine stands allowing you to rotate it 360 degrees, making it easy to access any part of the engine from a comfortable standing position. I may even buy one later as they are not expansive.

tcane · #5 06-06-2002, 01:07 PM

Glad to hear you were able to remove the IPTD shaft.

The roto gizmo is called the Roto Cap by M-B and it is very doubtful they are bad. The Roto Cap turns the valves slowly to let them wear evenly. Once you clean the oil out of the Roto Cap, check them by turning by hand they should turn freely with a slight click during the rotation (prevents the Roto Cap from turning in both directions).

I caution you not to make the head gasket contact surfaces too smooth when cleaning using a bead blaster. The cast iron diesel engines were designed with a specific roughness to the head gasket surfaces for sealing purposes (this was the technology of that time period). A too smooth surface will result in the head gasket not sealing properly and subsequent failure. A clean head gasket mating surface is needed, but not too smooth (once clean you can see the milling marks on the head gasket contact surfaces).

I assume you know to check the head/block for warpage? Check the cylinders for wear and replace the piston rings since you're there anyway (I prefer Deves cast iron alloy rings over the OEM chrome faced rings because the cast iron rings do not wear the liner as much as the chrome faced and if the bores are otherwise worn, but are OK for taper and out-of-round, cast iron rings will wear-in and mate to the cylinder walls better). That is, if you're taking the pistons out which I assume you've done since the engine is on a stand.

Exhaust valve guides usually wear faster than the intake guides - a go,no go gauge is what M-B recommends and clearance is tight compared to Detroit engines (valve guide ID 10.000 - 10.015mm, service limit 10.025mm, valve stem OD 9.92 - 9.94mm). Valves can be re-faced if needed. Lap the valves lightly with lapping compound to mate the surfaces to each other (even if a machine shop does a valve job, some do not take the time to do a good lap job).

My $0.02 Worth!
Tom

Stevo · #6 06-07-2002, 12:46 AM

* Glad to hear you were able to remove the IPTD shaft.

* The roto gizmo is called the Roto Cap by M-B and it is very doubtful they are bad.
* The Roto Cap turns the valves slowly to let them wear evenly. Once you clean
* the oil out of the Roto Cap, check them by turning by hand they should turn
* freely with a slight click during the rotation (prevents the Roto Cap from turning in
* both directions).

The roto caps seem to be ok Tom. Its this sort of thing that is important for the first timer to know.

* I caution you not to make the head gasket contact surfaces too smooth when
* cleaning using a bead blaster. The cast iron diesel engines were designed with a
* specific roughness to the head gasket surfaces for sealing purposes (this was the
* technology of that time period). A too smooth surface will result in the head
* gasket not sealing properly and subsequent failure. A clean head gasket mating
* surface is needed, but not too smooth (once clean you can see the milling marks
* on the head gasket contact surfaces).

Actually I did not get the head bead blasted today but cleaned it up myself with a brass cup brush on my 4 inch grinder. Maybe going over it with emory cloth wouldnt be a bad idea. That does make sense about the head being too smooth. Seems they would not do the bead blast with the pre com. chambers in. I was thinking that the magnaflux was the most important part of "cleaning and crack check"? Would you pull the pre com. chambers if the head comes up crackless?

* I assume you know to check the head/block for warpage? Check the cylinders for
* wear and replace the piston rings since you're there anyway (I prefer Deves cast
* iron alloy rings over the OEM chrome faced rings because the cast iron rings do
* not wear the liner as much as the chrome faced and if the bores are otherwise
* worn, but are OK for taper and out-of-round, cast iron rings will wear-in and mate
* to the cylinder walls better). That is, if you're taking the pistons out which I
* assume you've done since the engine is on a stand.

OK this is the part that requires measuring really small parts of inches to determine what size pistons I have. My MB teck, friend miked a piston and considering that I broke lots of rings getting the pistons out (ridge), determined I need new pistons. (which I sorta expected, 200k + on them) the lesson on using a micrometer reminded my that I should have been more attentive in shop class. So my quest tomorrow is to find a shop to bore the cylinders as I have a week or so until the crank is done.

* Exhaust valve guides usually wear faster than the intake guides - a go,no go
* gauge is what M-B recommends and clearance is tight compared to Detroit
* engines (valve guide ID 10.000 - 10.015mm, service limit 10.025mm, valve stem
* OD 9.92 - 9.94mm). Valves can be re-faced if needed. Lap the valves lightly with
* lapping compound to mate the surfaces to each other (even if a machine shop
* does a valve job, some do not take the time to do a good lap job).

I was figuring on replacing all the valve guides as long as the head is off and lapping the valves in with the compound. your comments they are worth more than 2 cents. Thanks Tom

tcane · #7 06-07-2002, 02:46 AM

Steve:

The Haynes manual is very good. Follow the steps in that manual and your engine rebuild should turn out good.

A brass brush probably did not remove metal, only gasket material. The gasket surface should be OK for sealing puposes without using emory cloth.

Why are you bead blasting the head?

Magnafluxing is a good idea. If the head is not cracked, and the pre-chambers do not show signs of damage, then leave them in. Look at the portion of the chamber extending beyond the surface of the head at the ports (drilled holes), if the ports have some build-up then clean the ports until the build-up is gone (I used a brass brush on the surface and then a small drill bit to clean the port hole, turning the bit by hand), do not open/enlarge the ports up when cleaning, you want a clean port so the injected fuel has an even pattern coming out of the port. Inside of the port area of the chamber is a raised area to disperse the fuel evenly, so you cannot run a drill bit the size of the port hole all the way through to the port on the opposite side.

Sounds like you will have the cylinders bored to fit oversize pistons. Ask the machine shop what experience they have with 1975-1985 M-B diesel engines. Perhaps your friend with M-B experience will know of a good local machine shop or the shop doing your crank.

Usually, when you buy replacement pistons they come with rings. So, you will use those rings unless you want to spend more money for other rings.

When you get the block back from the machine shop it needs to be cleaned. Use hot, soapy water and a scrub/parts brush to clean all the grit/metal particles out of the cylinder bores and the rest of the block including oil passages. I rinse with clean water applied with the brush. Wipe the block dry (I dried each cylinder as I finished it) and wipe oil on the metal surfaces including the cylinder bores immediately to prevent rust. Do not use solvent to clean the block, only use hot soapy water because solvent will not remove the grit/metal particles especially from the bored cylinder walls. The grit/metal particles in the cylinder walls can only be seen under magnification and will come out when the engine is running to ruin your rings and score the cylinder walls/pistons (effect on the rings is the worst). Ask the machine shop you use about cleaning the block after they finish working on it - perhaps they will clean it for you for a fee if you do not want to.

I use assembly lube to lubricate parts instead of oil.

After installing the engine you can also build a bit of oil pressure before starting the engine by leaving the glow plugs out, turn the engine over say 1 - 1 1/2 minutes and let the starter cool for 2-3 minutes, repeat turning the engine over for 1 - 1 1/2 min., let the starter cool off, use a battery charger/starter combo to keep the battery charged and help turn the engine over, keep repeating this procedure until the oil gauge moves just a bit when the engine is turning using the starter motor (meaning some oil has filled the oil passages/crankshaft, camshaft bearings, etc.) and at the same time you've primed the injection pump and nozzles with fuel (hand prime the injection pump before the procedure to build oil pressure). Once the glow plugs are installed and connected to the electrical supply, the engine will start right up with oil pressure almost immediately.

The Haynes manual has a good break-in procedure located at the end of the engine rebuild section. I would add that the initial procedure to mate/seat the rings to the cylinder walls should be done say 30 times instead of 10-12 times.

Good Luck!
Tom

Stevo · #8 06-07-2002, 11:23 AM

" Why are you bead blasting the head? " Good question Tom, Guess I figured it was just something you do. Its nice and clean so maybe all it needs is magnafluxing? The pre chambers seem OK, that is the "sticking up" part did not have any plugged holes. I will take a closer look and run a drill bit in now that you have told me about them. I had no idea what a pre chamber looked liked before this.

The shop sent the crank back so I could pull the timing chain gear and pilot bearing. The gear looks good but I spoz the bearing and keeper ring should be replaced. Anyway the crank should be on the way to the shop.

Looks like the next step is to determine what size pistons are needed, get them so the machinist (found a good one) can bore to fit, finish the head, guides, and lap job. Gota get some time to get beans planted in the garden which may happen with the crank and block being worked on.

Thanks Tom for all your help

tcane · #9 06-07-2002, 07:05 PM

Stevo:

When its time to plant crops, ya gotta do it. Time does not wait for crops, while an engine rebuild can wait a couple of days while you plant your crops. I assume you're planting according to the moon cycle?

You may want to replace the timing chain gear if worn (about $29 US) since you are removing it and replacing the crank spacer (part that fits in front of the timing chain gear on the crack and the front crank seal fits over, about $9) and the pilot bearing (about $9). When removing these parts I had some difficulty because the last person who replaced the front crank seal drove the locating pins a bit off line causing the notches in the crank to deform a bit. I found the high spots and used a file to reduce the highest areas, then used progressively finer grits of sandpaper (100-220-400-600-1500) to smooth only the high areas down so the timing gear and crank spacer slid on easily.

If the head cleaned-up nice, then bead blasting is not needed - unless you just want to do it. I cleaned my head really well, cleaned with isopropyl alcohol, and painted it with engine paint (block also and many other parts). If you bead blast, the original coating will be gone, and the head will rust in some areas - so I suggest painting it it if you decide to bead blast. Painting the engine gives the engine that professionally rebuilt look - so go for it, it will really look great after all the work you're doing!

!

Good Luck!
Tom

psfred · #10 06-07-2002, 10:14 PM

You actually have two choices with the pistons -- get oversize and bore, or get standard and re-sleeve the engine (all MB engines are sleeved). Sleeves are $35 or so each, and will cost $10 or so to remove and replace plus about $35 each to bore to fit pistons.

The thing to keep in mind is that the crank will have to be re-balanced if you change piston size, and this will cost about $100-300 if done by the same kind of shop that did my brother's. Big pain in the butt as the crank is nitrided very deep and cannot be drilled, all the balancing must be done with the flanges and flywheel.

I'd personall go for new sleeves and standard pistons, but you can get more horesepower with the oversize ones. The cost the same, the only difference will be in getting the sleeves replaced vs balancing the crank.

Peter

Stevo · #11 06-08-2002, 01:15 AM

Ya, the bean crop. I know I should wait for the right moon cycle but it seems if I have time to get any in at all that will be an accomplishment and who knows maybe the moon will be right anyway. the way the weathers been around here this spring i am not staking the farm on the tomato or bean crop.

The timing chain gear looks ok and I am thinking the spacer should be replaced anyway. Think i will replace the oil pump too as it did run dry and for $ 100.00 bucks it seems like a good idea. I would think replacing the pilot bearing a good idea too. Peter has brought up something I had not heard about. The crank balance verses selves issue. I am not committed to doing things either way at this point as I would assume the machinist could do a liner job as easy as a bore job. If I wonted the crank balanced though I would have to let them know....Hummm.... I just figured they sent it back re-balanced and ready for any pistons, but what Peter is saying is that if you dont change piston size it does not have to be re- balanced but if you change piston size it MUST be re- balanced. Guess I better check into this on Monday. That leaves plenty of bean planting time this week end.

Tom ...I will paint her up real nice when the time comes, which seems like a long way away at this point.

Thanks Guys

this point........Thanks Guys

tcane · #12 06-08-2002, 01:45 AM

Fred:

You are wrong about the engine balance on the 240 and other M-B engines, just like the last time. Then you used a 1972 manual for a "6 cylinder" 300D engine made in the 1960's to tell a member owning a "5 cylinder" 300D engine made 1975-1985 that the engine was not dynamically balanced as a unit after assembly. Wrong. Now, you are wrongly saying that if the pistons are replaced that the engine has to be balanced - wrong! Pistons move in a linear direction and do not affect circular balance due to centrifugal forces. The M-B engine manuals and no info/classes I own/attended ever require re-balancing an engine when just replacing pistons. The only requirement when replacing pistons is that they are all close in weight - here, the 240/300 engines require a 10 gram spread. And pistons for stock (not racing) engines, including M-B, are not weighed, sorted, and grouped into weight categories like other parts - like rods. If a rod is replaced, then yes a rebalance may be needed unless the new rod(s) are matched weight-wise to the old ones - M-B groups rods in 5 weight categories with only a 4 gram difference allowed. However, rods move in a circular motion (and a bit of linear movement close to the small end) and require much closer weight matching than pistons do shown by the 4 gram grouping spec. versus 10 grams for the pistons. And the greater mass at the big end of the rod and its subsequent effect on centrifugal force due to its circular motion has far more effect on engine balance than the much smaller mass of the small end of the rod that is moving linearally along with the piston's movement. Actually, the 10 gram spec for pistons has more to do with the mass of the piston accelerating after combustion and the uneven force applied to the crank if the pistons are not close in weight - not engine rotational balance.

M-B 240 crankshafts are not balanced as you wrote. 240 engines are not dynamically balanced. Instead, M-B balances all balance plates (we call them harmonic balancers) and all flywheels to a specified spec., then the balance plate and flywheel are assembled onto the engine. No other balancing is done to the 240 engine, other than the aforementioned rod and pistons. All 240/300 flywheels have an index mark on them and a matching index mark on the crank. The balance plate is indexed to the TDC of piston #1 using the timing pointer. Only the 300D engine is dynamically balanced after the engine is fully assembled. Your brother spent money he did not have to for balancing his engine, unless he or the rebuilder made a mistake.

Replacing the liners to use stock piston bore diameters is adding an un-needed cost of about $250-$300 - and you overlooked the probable need to mill the block for another $50-$75. Oversize pistons come in .25mm and .50mm sizes and it would be very unlikely that the liners need boring to greater than .50mm oversize. Also, any slight power increase using .50mm oversize pistons resulting in a huge 2 cu. in. increase in displacement could only be determined using a dynometer, if any increase in power registers at all.

I've built 1,000's of engines and many 100's of racing engines (large displacement Detroit V-8's turning 8,000-10,000+ rpm and motorcycles 500cc to 1,100+cc turning 12,000 to 16,000+rpm) and your comments and suggestions about engines have no basis in fact. Please, do not continue to write mis-leading comments.

Tom

leathermang · #13 06-08-2002, 11:09 PM

Stevo, Sorry I missed your reply to me until just now... I can tell your pretty much hooked,,, it is fun to take apart a well made machine....and tools like that engine stand are wonderful for fun and speed.... and help your back.... It sounds like you have the makings of a great FAQ page,,, particularly looking forward to seeing what you learned that was not in the manual , Greg

1980 240d manual

I wish you and that 1980 parts car lived closer to me....

Stevo · #14 06-10-2002, 01:47 AM

Leathermang...Ya, just about any place in the country is a long way from the "upper left-hand corner" here. If you are ever in the mood for a road trip, the Olympic Peninsula is a nice place to visit in the summer and might be a contrast to your part of the world. My people, on my Dad's side, are from Texas. My great, maybe great ,great Uncle Buck was a Texas Ranger and I still have lots of second or third cousins out there.Maybe I should take a road trip some day. I think I would hook up the AC first.

I am still having lots of fun and I am at the point where I am waiting for the crank and head to be done so we can order the pistons. I would like to be getting the replacement stuff from Fast Line and / or Rusty,but my MB tech buddy that is helping me has his supplier. As far as the FAQ page, I have been trying to figure out what I could take a picture of (if my wife can find the camera which is buried amidst all the books in her van, she's a teacher). Seems like any tech stuff has already been photographed better than I could do it and is available in the manuals anyone doing this job should have anyway. I could get some shots of dropping the engine in when the day finally arrives, anyway let me know if you have some ideas. What has been valuable to me is reading other posts about the different options at various stages, for example, do the head yourself, or send it out?; just do what is necessary to "get her back on the road" or replace everything just to be sure? You know what I mean, all the different options including getting a short block or long block. Tom, as you can see is a wealth of info and seems patient with rookies like myself. When I got in a timing device bind, Tom was able to explain how to bale me out. I will start another thread in a week or when I get the parts back and talk about installing valve guides or what ever else comes up then putting the engine back together.

leathermang · #15 06-10-2002, 11:31 AM

Stevo, If you would have to hook up your ac just to come to Texas your family must have lost the hardy genes it had here in Texas ..... It was a balmy 97 with 80% humidity two days ago.... If there is a fall get together here in Austin I am planning on somekind of trophy for longest distance traveled.... hard to imagine anyone beating you if you decide to come to it....

Greg