Christine: I would have to say yes, with the understanding that I have never pulled the engine out of a S10 Blazer. Not having to deal with the transmission and transfer case; I again think it is easier.

So I am retracting the statement I made several times in this thread.....and say the opposite....removing the diff is the way to go to replace the oil pan gasket and timing cover.

Note that I said removing the diff...not just dropping. To have the diff out of the way when installing the oil pan, makes life so much easier. Of course I am hoping that I am able to put the diff back in the way I saw it come out...and as one piece. Putting the right-side axle tube on with the diff in is not all that difficult, messy due to the RTV, and need to let it set for a good 24 hours for the RTV to cure.

I was reading the TSB on installing the timing chain tensioner; it shows 7.5hrs labor hours, and only lowering the oil pan enough to get the timing cover out. I cannot see how this would work as the RTV seal at the rear would likely be destroyed...which would then leak. An example of how one repair leads to another repair.....how shops make $$$$.
Also the timing cover needs to be modified, which the TSB says nothing of. The cover needs to have material removed to clear the timing chain tensioner bracket, otherwise the cover does not sit flat against the block...and is likely to leak. Another planned repair....?????

Later,

 

Thought I would share the timing cover modifications that I think are necessary in order to have the timing chain tensioner.
Picture 1: the new Pioneer timing cover. Note the two molded alignment pins above the two bolt holes, on each side of the crank seal.
Picture 2: modified Pioneer timing cover. Note the two areas where the alignment pins used to be. Drilled and clearance'ed for the timing chain tension bracket.
Picture 3: the tensioner pins as installed; the shinny metal posts with the bracket under.
Picture 4: tensioner pins after being shortened.

Along with the timing chain tensioner are two pins that are driven into the block to hold the tensioner bracket. Problem is, these pins now protrude 5/8" above the surface. You could drill the timing cover clearance holes that deep, but this depth does not allow much error as the timing cover is only slightly thicker than 5/8". So I used a Dremel tool and shorted the two pins.

The cover now fits flat against the block. I am still going to add a thin layer of RTV along the gasket for a better seal.

Picture 1:

Picture 2:


Picture 3:


Picture 4:


Still asking myself.....why did I install the timing chain tensioner.......

Later,

 

So the tensioner is not stock?

 

Christine - nope...the tensioner is not stock. TSB 03-06-01-024B....complaints from 4.3L V6 vehicle owners of a noisy timing chain. I went ahead an installed it as it really takes-up the slack in the chain. Think I have been working on Honda motorcycle too much lately....most have chain driven cams with chain tensioners on them....so this looked to be a good to add and probably is.....just requires cover modification since it seems that no supplier makes a cover that fits with the tensioner installed. Am not 100% sure that the GM cover (89017259) is modified....could never find a picture of the inside...and was not going to purchase one as it is quite expensive compared to others.

 

UPDATE: timing cover is in; used RTV on the gasket this time, just to be sure.
With the old oil pan gasket just pressed into the oil pan, I did a couple of dry-fits onto the engine to get the angles needed. I found that the two rear studs would easily pull the gasket out in the process, so I removed them from the engine.
I also applied small dabs of RTV to the corners of the oil pan to "glue" the gasket in place.
In checking the fit of the oil pan gasket to timing cover, found it was a rather loose fit. So unlike the SBC 350's I have done in the past, where have had to use silicon spray to get the gasket to go into the timing cover. So in addition to applying RTV to the areas shown in the FSM above (thanks again Tom A), I applied RTV to the entire timing cover area, made a bed of RTV for the gasket.

Installed the oil pan, got all the bolts/nuts torqued down. Then installed the oil filter adapter. And that was it for the day as the RTV needs 24 hrs to fully setup.

Putting the oil pan on does require several angles due to the crossmember and the oil pump.....and must not forget those blasted transmission cooler lines!! I so want a manual transmission in the Blazer.

Later,

 

After following this thread, I'm glad I didn't install a chain tensioner. And I'm also glad I completely removed the crossmember from under the oil pan when I did my SAS. I just have to unbolt my custom crossmember and my oil pan drops straight down. Not trying to rub it in or anything...

 

Just FYI, as I also did the tensioner when I rebuilt mine... The AC Delco covers are designed to work with it with no modifications needed. Yes, they're significantly more expensive, but I really didn't want to chase down a cover leak later on, and you can feel the difference between the factory and aftermarket covers.

 

What AC Delco timing cover part number did you use? Was it the 89017259? I would think that this cover would clear the timing chain tension...but as I said above, I could never find a picture of the inside to verify this and did not want to spend the $80-$120 for the GM cover to find-out when the Pioneer cover was $16.

Thanks for the FYI.

 

Have done two test engines run with no oil leaking, so I am calling it good. Got busy and got the diff back in....and was able to with it all assembled too! I tried to put the diff back in the way it came out....but just could not keep the diff on the jack puck. So after stopping for several minutes to look and think, I tried with the diff's nose up...got it to a point....then was able to push it into place and get the jack back under it. YEAH!

Got all the bolts in and that was it for the day. Still have the CV axles and brakes to put back....should not take long....then ready for the road test.

Hope to have the Blazer on the road on 5/21.

Later,

 

Well....it has been a long road here....but the Blazer is on the ground again, just need to bleed the air out of the cooling system, will probably take a couple of short trips to get all the air out.

But the task is done.

Later,