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-   -   93 D21 4x4 Head Gasket Advice (

Hoseman1958 05-03-2021 09:51 AM


Originally Posted by XoXSciFiGuy (Post 548794)
Oil pump should go in first...and THEN the distributor on top. Reason is because once you have the oil pump in place properly, the shaft cannot move on you as long as you don't roll the truck while in gear. I guess you COULD do it backwards, but I haven't tried that. Remember....just one tooth off on the oil pump gear will toss the truck about 20 degrees out of time. If the gear has 16 teeth, (can't recall the exact number of teeth, but it is something like that) that puts off the timing at 22.5 degrees. Yeah...that engine will buck and rock and backfire even if it starts.

Thanks SciFi. I set TDC with oil pump out then....insert oil pump shaft per factory service manual pics....and attach distributor. I'm game to give that more than a couple of tries. Thanks for the pointed advice on shopping for an oil change. Frugality is important! I have changed oil on this truck every 3K miles. Will now start doing it every 2K miles!

Hoseman1958 05-07-2021 06:13 AM


Originally Posted by Foul_Mouth (Post 548787)
You will want the pump out before you set the engine to tdc.

Success! I removed the oil pump and put #1 on TDC. My neighbor held the rotor in place to point to the original paint mark on distributor housing. After a few tries, got the oil pump inserted into the distributor using pretty much the exact angle shown in the FSM. The truck started right up.......and is now running like a sewing machine! I'm elated!

I drove it for 5 miles or so and saw oil smoke. We had stripped out probably 3 of the valve cover bolts weeks ago when I put it back together the first time after timing chain fix. My neighbor rigged up a temporary fix using 1/4" 20 thread hex bolts with some nuts just below the bolt heads. This may not have been a good idea. Oil is spewing from the valve cover. I am having surgery today and won't be able to attend to anything for weeks.....but at first opportunity, will be looking to get the valve cover "battened down." Neighbor says that we can tap out the valve cover holes and use the same type of hex bolts. My preference at this point instead, would be to hear from the forum about how to move forward with this process.

I can't thank you guys enough! I would have never been able to do this without the generous attention that I have received from everyone on this thread. Ya'll have been awesome!:dathumb:

jp2code 05-07-2021 10:05 AM


Originally Posted by Hoseman1958 (Post 548902)
I am having surgery today

Good luck today

alabama_lowlife 05-07-2021 05:26 PM

Yeah, good luck man, I hope everything goes well on the surgery.

You can drill out the holes in the head to a larger size and use a helicoil to repair them. Get some M6x1.0 helicoils from the local parts store.

XoXSciFiGuy 05-08-2021 12:09 AM

When installing a valve cover gasket, even if you install the helicoils to do it..don't overtighten the valve cover bolts. You will bend the lip of the valve cover every time. There is no real oil pressure under that valve cover. Oil just splashes around. Let the gasket and sealer do the job and no more than 8-10 pounds on the bolts. With a Nissan aluminum cover, the risk is more that you will crack a corner of the cover, though. Around the bolt holes. The lip bending is more for steel covers.

Ask me how I found this out a looong time ago.. :bang: Back in the late 70's I bent the lip on one steel cover so it always leaked. And I cracked the corner on a Nissan aluminum cover.

Hoseman1958 05-24-2021 07:12 AM

So....about 4 of the valve cover bolts stripped metal out of the cover. My neighbor suggested buying 1/4-20 x 3/4" (US) bolts and using those as replacements. We did this w/o tapping the holes. Tightened crosswise by slow degrees all around and drove the truck aggressively for @ 10 miles. Right now there is no evidence of any kind of oil leak from valve cover, timing chain cover, or oil pan.

There is no coolant leak either.....and the truck runs better now then before I tore it apart. I couldn't be happier with this outcome! I hope that this thread will serve as a guide for avoiding some of the pitfalls that I encountered.....even though I was warned about them here in the forum...... like overtightening into the aluminum. It also goes without saying that you should always make sure that you have removed the crank bolt before trying to pull the harmonic balancer...ha ha!

The single most important observation I might like to cite about the process though is that so much time was wasted by not paying attention to the initial paint mark I made on the distributor to record the position of the rotor pointing to # 1 cylinder while on TDC. By noting the orientation of the half moon on the distributor shaft......and then re-inserting the distributor with an assistant holding the rotor in the exact position pointing to the paint mark, it only took a couple stabs of the oil pump up through there with half moon on the oil pump shaft oriented exactly opposite to the half moon on the achieve success.

Thanks again Ya'll for the unselfish sharing of your time and insights! I would never have dreamed that I could do this!

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