I'm trying to choose a DTI which I can use to find TDB on my om603 engine. The head is installed and I think I fouled up setting TDC when I put everything back together. My hope is to remove the #1 injector and the precombustion chamber so I can insert a TDI to pin down exactly (or as closel to exact) TDC.

From looking around the net - I thought I wanted the Starrett 196, but after looking more closely at that one, I don't think it'll work. The lever on that one looks like it is on the back of the dial. What I need in one with a long stem that will reach down thru the injector port. One that I can clamp in place - probably the kind that has a little pivoting finger. Since I am not actually interested in a measurement value per-se, only the movement of the piston, there is no need for a calibrated / certified uber-fancy tool. I even have thought I could maybe use a long wooden dowel which I could watch closely as the piston moves up/down?

Anyone have a suggestion? I am hoping to find one used.

Thanks to all for the advice.

This is because you have reason to believe that the crank shaft is not matched to the numbers on the pulley?

I believe you may be over-complicating this matter (I am often guilty as well).

It would be much less invasive to remove the pulley and make certain it is correctly mated to the crankshaft - it only goes on one way fitted to a woodruff key.

The accuracy required for a head installation (unless it was milled) is 18 degrees on the crankshaft; this correlates to one chain link. That is easily achieved without a dial indicator.

However, a Starrett would be nice, but cheaper makers/ models are available and meet the needs of general DIY for these cars.

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Try to line up zero on the crank pulley to the indicator on the front of the engine.

then the cam sprocket goes on with its own TDC markings lined up and the crank still at zero.

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The only reasons I can think of to find TDC with a Dial Indicator is if something hppend to the Pointer or the Crank Damper Dowels have been messed up and Damperneeded redrilling for new Pins.

However, you can purchase Extension Shafts for the Dial Indicators. Extensions for a Metric Gauges have differ threads from the Inch type gauges.
You also can get different shapes got for the end.

If you have Extensions long enought to go where you want and you can properly position the Guuge it does not matter if the Plunger is on the back or on the side.

However, the Gauges with side mounted Plungers tend to be made with more range of movement.

If you are speaking of what is commonly called a Last Word type Dial Indicator that has the tiny little lever on it I don't think that it can be used for this particular application you have in mind.

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84 300D, 82 Volvo 244Gl Diesel

Problem is I removed and cleaned the crankshaft indicator. It has a lot of room for adjustment and I hadn't yet attached the cam sprocket. So, I fear that I'm off a few degrees. Nothing hits, it just won't start. Thinking I'd rule out timing by setting TDC this way. The Starrett 196 won't work for this because the plunger is short and is located on the back of the dial, I can't see a way to make that plunger reach all the way into the piston.


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1987 300TD named Klause
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If you have access to a drill press and some hardwood, it would be easy to get a piece of hardwood and put a hole in the end of it to act as an extension. You can choose between friction fit or setscrew, as long as the hole can accommodate the quill of the dial indicator. All you need is an extension rod by the sounds of it.

That is not a problem.

The indicator on the engine is still accurate enough to get the chain lined up on the crank and the cam with the correct relationship.

Please do not go removing your prechamber... you are asking for trouble.

It would be easier to remove the camshaft and the lifters on the #1 cylinder and find TDC by depressing a valve. A bit of trial and error will get you the least valve movement - then you're at TDC.

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Stretch mentioned the Method for 617 Engines but said to remove the Valve Spring and when the Piston is near Top Dead Center let the Valve drop down on the Piston Head. But, He said to use a Dial Indicator.

I have never seen what the Valve Train on the Newer Engines looks like so cannot comment if the above method would work on them.

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84 300D, 82 Volvo 244Gl Diesel

its not as easy to remove the spring. he would need to push the valve against the piston to remove the retainers.

but its doable.

A dial indicator would be much more accurate, but its not necessary here.

The inaccuracy of doing this by feel via trial and error is comparable to the amount of 'slop' in the chain line and sprockets.

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It depends on how you look at it. If the Cranshaft is off one degree it is only 1/2 degree off at the Camshaft.
If the Camshaft is off one degree it is off 2 degrees on the Crankshaft.

Also the Pointer is used for the Fuel Injection Timing.

For myself I do not mind bying Tools when I have a need for them (or making them if I can). The OP might find the Dial Indicator useful in repairing someother part of the Car later.
The Harbor Freight Dial Indicators don't cost much and are adequate for Automotive use.

And in the OPs case the Prechamber Tools can be rented.

Autozone has a free rental on an entirely adequate Slide Hammer but most of the Prechamber Pullers are threaded for Metric threads and the Autozone one is 5/8"x18 or 16 threads. I cannot remember the number of threads right off.
So the OP would need to come up with an adapter or find a slide Hammer with the Metric threads on it.

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84 300D, 82 Volvo 244Gl Diesel

Or move the piston up to near suspected top dead centre. Fill with light oil. Watch for the point where the oil stops leaving the injector hole. This when you slowly move the piston upward.

Insert and seal in the injector port a small tube to vastly increase the accuracy of the test to start with is still better. You of course watch the oil rise in the tube. Even a clear straw ids good.

You can go back and forth just a little to average the tdc. This is as accurate for general purposes as a dial gauge would be.

I used the HF one. The shaft is not quite long enough but I was pretty sure the margin of error was minimal.

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If you want to use the dial indicator, mark the damper with a valve depressed a nominal amount (say .050-.100") on the upstroke and then the downstroke. Split the difference on the damper and that's true TDC. Simply trying to measure TDC any other way does not account for the relatively small movement of the piston at TDC while the crank continues to rotate.

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'83 300D, 126K miles.

yup, what he said...

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That's why with the liquid method or dial indicator you average the two sides of the reading. Using a straw gives greater accuracy. The volumetric differeance is great then. Beats pulling the prechamber as well.

On an old engine components of the valve train have wear issues to deal with to use the valve method.