R&R OM-603 Cylinder Head
 

The turbo oil seal was leaking on my 1991 350 SD. Turbo and manifold was removed and I discovered the exhaust stud nearest the firewall was broken off about 3mm below the surface. I can't seem to remove the stud with a screw extractor. There's a 1/8" hole drilled into the center of the broken stud and the stud actually rotated and bottomed into the tapped hole while drilling with a right handed bit. Now I think removing the head is my only option. Can someone provide instructions (or a link) to remove and replace the head?

Thanks in advance.

Greg

I'd recommend you get a left handed drill bit in a slightly larger size than the existing hole and try that. If the broken part moves in, it will probaly come right out.

x 2

First drop some Kroil down the stud's remains. Then go to a easy out.

Thanks for the encouraging feedback.

In the event that a screw extractor doesn't work, does anyone have the head R&R procedure? The engine has accumulated 202,000 miles and I'd be interested in looking at the cylinder bores and checking for potential connecting rod bending.

Greg

head removal...
 

The camshaft is the key to removing the head ....There is a proceedure for that ...whats your location??

Since nobody's biting, ... open the hood, ...

Special tools you'll need are some rubber/plastic caps, 12 of 'em, to keep the injectors and injection pump outlets really clean, best to get some good ones from the local hardware store before you start, a nice deep 27mm socket for the injectors, a selection of allen-wrenches/bits including (I believe) a 5.5mm for the difficult to remove ones around the turbo, and a wobble-extension for the socket-head bolts holding the intake manifold. If you're replacing the timing chain, you'll need a chain breaker and chain rivet tool, if you're leaving the chain on then you won't, but you will then need a puller for the upper chain guide pin (the one that sticks out of the upper belt-tensioner shock mount). Triple-square bit for head bolts, long one is preferred to leave the cam in place.

Set the engine at TDC.

Drain coolant from the engine.

Take pictures of the wiring to the sensors and soft fuel lines on the head and remove the wires.

Remove the air filter, and then the heat-shield between the engine and filter area. This makes turbo and exhaust manifold removal much easier. Get the exhaust pipe knocked off of the turbo outlet early in the game with the turbo still attached so that you have something to work against, worked better that way for me.

Remove the belt tensioner shock/spring and upper mount from the head.

Remove the upper radiator hose, remove the heater hose from the rear of the head.

Remove hard fuel lines, intake crossover tube, intake manifold. Remove turbo, don't forget about the oil-return line from the bottom of the turbo to the lower part of the block. Remove exhaust manifold.

Remove Glow-Plug Wires.

Remove the cam-cover. Ensure that the timing marks are at TDC.

Remove the timing chain tensioner: It is on the passenger side, about half-way down, remove the large nut not the smaller one, you want to pull the whole thing out.

If you are leaving the timing chain on the engine, zip-tie the chain to the timing gear, remove the bolt from the end of the camshaft and lay the gear in the opening.

Pull the pin forward-out of the head that holds the upper end of the chain guide, remove pin and guide. The pin removal "requires" a slide-hammer, many of us have done it with a bolt and washers or other method. If yours is really stuck, can be a problem.

If you have the long triple-square bit for the head bolts, you can start to unbolt the head now as it will reach the head bolts under the cam towers (all-the-way through). If the shorter one, then you'll need to remove the camshaft first.

If camshaft, consult the proper bolt loosening/removal sequence so that you don't risk breaking the camshaft, and remove the camshaft. The bearing caps for the camshaft are numbered, but not the lifters. If you're re-using the lifters it is best to mark them now to ensure that they don't get mixed-up.

If you're going to remove the injectors, IMO this is a good time while the car is holding the head in place, makes it easier to turn the injectors. Same thing with the pre-chambers, this is a good time to break the lock-rings free (special tool, not mentioned above).

If removing the head bolts now, consult the FSM for the proper sequence to lessen the possibility of cracking or warping the head.


I'm sure I left some things out, and hopeful that someone will come and add them in now that there is a start.

Good luck.

Jeff thanks for the reply. This job doesn't appear to be too bad. I'm concerned about getting the timing correct when it's time to reassemble. Last year, I put in new injector nozzles and pintles and also pulled all the pre-chambers, cleaned and reinstalled. I don't want to pull them again if it isn't necessary. If I remove the head, what parts would you guys recommend changing? Timing chain, guides, any other parts? The engine now has 202,000 miles.

Anthony, I'm located in central New Jersey.

I look forward to any additional input.

Greg

X3

I think the left hand bits have only failed me once out of at least 30 tries.
But don't forget to put your drill in reverse mode!

Charles,

I have a 1/8" hole in the stud at this point. What size L.H. bit do you recommend?

Greg

Greg ...contact me if you need help..
I have a set of easy outs...

Where are you guys located?? Im in Wall (exit 98):)
Im going to have to tackle a head gasket in a 350 sdl ( I hope thats all) in the next few weeks.

Rick,

I live in New Brunswick. I'm going to try one more time to remove the broken stud without pulling the head. If unsuccessful, it will be time to round up the pin puller and special tool to remove head bolts. Do you have a manual for this engine? PM me to coordinate.

Greg

Greg, Ive got the factory manual. Im about 30 minutes south on rt 18 in Wall. If you want to drive down and borrow the manual you're welcome to. I can lend a hand depending when you need one. Im an airline pilot, and don't have a real regular schedule, and most of the time I am just on call....so I could help out, just know that I might have to leave when the phone rings. I'll pm you#

Replacing Cylinder Head on OM603
 

I will be replacing the cylinder head on a '91 350 SD soon. An engine rebuilder familiar with this engine suggested that I drain the oil from the hydraulic lifters. He claims there is a possiblity that the lifter plunger might inadvertently extend (due to the internal lifter spring force) and the travel of the valve could initially be too deep into the head (making contact with the piston). He also stated that returning the lifters to the original locations is not followed in his shop.

I have not seen this draining procedure in any of the cylinder head R&R instructions. Anyone have an opinion in this?

Greg

Did he give any clue how that internal spring in the lifter is going to overcome the load of the valve spring..........:rolleyes:

I've never heard of it.

If he has a marker, he can number the lifters and return them to the correct positions. Not doing so is probably not critical, but sloppy.

Draining OM603 Lifters
 

Brian,

I got a demonstration on how to disassemble lifter number one. This guy claims they have attempted to collapse a lifter with an arbor press to expel the oil while applying as much as 8 tons of force, to no avail. The disassembly procedure he demonstrated was holding the lifter in one hand, slaming the lifter onto a thick steel surface and the shock applied, will cause the plunger to fall out after 3 to 4 hits. Then the spring and seat etc. can be removed. We then went over to the parts washer, cleaned the components and put everything back together. The plunger now moves freely since the oil has been removed.

I've tried my best to describe this process. Are you confused yet?

He also said the engine will really run poorly until the lifters finally fill up.

Comments anyone?

Greg

I've heard more than enough about this "mechanic".

If the risk is real yet somehow not mentioned in the FSM, isn't it easier to keep track of which lifter goes over which valve? An egg crate is perfect for this.

I've never heard of slamming lifters to shock the check valve into releasing. In a Mitsubishi I had the FSM said to stick a pin into the lifter to displace the check valve to drain the lifter before reinstallation, but only after pumping them in a bowl of oil to check that they're working.

Sixto
87 300D

X2

Slamming a hardened steel lifter into anything other than wood tells me that this guy is a hack.

The lifter is essentially a hydraulic damper. It fills with oil, the cam lobe will shove it down, the oil cannot escape fast enough to collapse during the very short (1/10 second at idle, shorter at higher RPM) time it is compressing a valve spring. If held under pressure (such as during engine assembly) it will collapse unless there is something very wrong with it. Holding it in your hand, you can press it together and force the oil out.

If he has tried to do so on a hydraulic press, he's an idiot to begin with, and the reason it did not compress is because it was already compressed.

First, I would run away from this shop. If I were so un-concerned with his lack of automotive knowledge and further, his lack of understanding that he might be wrong (which will come back when there is a problem later, and he can't believe the he messed up = you're screwed) to actually let him touch my car, I would tell him to get a black marker and take off his shoes before removing the lifters, so he can count to twelve and write it on the lifters.

He'd only need to take off one shoe..............;)

Thanks for your input guys. This oil draining procedure didn't make sense to me either.

I used a Plano tackle box to organize parts as I removed the head. When the lifters were removed, I used a few shop towels, brake clean and a Sharpie.

Greg