Best way to find TDC

CD-powered vehicles, specifically the Sentra, but also retrofits and swaps.

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bmktw2
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Joined: 8 years ago

Best way to find TDC

#1

Post by bmktw2 » 6 years ago

I'm about to remove the injector pump to get it rebuilt. I've never worked on a diesel and am kinda lost on how to find TDC on the compression stroke.

I also want to do a compression test just to check to engine out. Does anyone have any advice on that aswell?
Thanks!

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

#2

Post by Nissan_Ranger » 6 years ago

You can remove the valve cover and watch the valve function for #1. Once the intake valve closes, the next half revolution of the crankshaft will be the compression stroke and you will feel the compression on #1 piston resisting you as you turn the crank. When the piston reaches TDC, the timing marks will coincide at the same time that the effort of turning the crank drops off next to nothing. Any four cylinder inline engine crankshaft will have virtually zero resistance to turning when the pistons all reach TDC/BDC as they momentarily stop moving as they cross over center, thus momentarily offering no resistance to the movement of the crank...

HTH,

N_R
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

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asavage
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Re: Best way to find TDC

#3

Post by asavage » 6 years ago

bmktw2 wrote:I also want to do a compression test just to check to engine out. Does anyone have any advice on that aswell?
Use a Snap-On diesel compression tester set. See this thread for info.

The special SD adapter I had made is not necessary on the CD, IIRC.

Avoid Harbor Freight quality compression testers. The whole point is to get a reliable compression reading, and HF's stuff can't be trusted.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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