Texas CE

I am replacing my water pump/opti/ timing cover seals and have some questions:

- The front crank seal I purchased from the dealer has little bumps in it on the sealing surface that contacts the crank. The old seal just has little diagonal ridges. Any idea why the difference?

- According to the position of the pin for the Opti I am at TDC #1 but the key way on the crank is not on top (although the arrow on the hub was also pointing at TDC #1) Does this matter?

- Why is the hub not keyed to the crank? I am worried about it spinning on the crank and the HB being out of synch with the crank.

- I pulled the crank sensor because it was soaked in fresh oil. It had been leaking for awhile. When I pulled it I noticed it was covered in rubbery form-a-gasket. Is the form-a-gasket stock? (I am thinking a previous owner pulled it because it was leaking and decided to do a band-aid fix).

Thanks to everyone for their support!

96GS#007

Sounds like you're looking at the seal and it's still in the package. The gray "bumps" are grease to lubricate the seal material.

The key on the crank will not be at TDC when the #1 piston is at TDC. It should be around the 1:00 position when viewed from the front. The opti is keyed to the cam. As long as you install the opti correctly, there won't be an issue. Yes, the later Opti can be installed incorrectly. When installed correctly, it'll sit flush against the front cover without the bolts securing it. If you have to use bolts to seat it, the opti is on wrong.

Why is the hub not keyed? Cause GM made it that way. Unless you have a blower or you've r&r'd the hub multiple times, it's not an issue. Aftermarket keyed hubs are available for a couple hundred dollars if it makes you feel better.

RTV around the crank sensor isn't factory. The sensor has an o-ring (available separately from GM). Often times an oil leak past the front crankshaft seal is confused with a leaking crankshaft position sensor seal.

tjwong

When on number 1 the opti cam drive pin will be at about 9:00 position.

Hey Jim, quick question for you. Your crank position sensor on the bottom of the timing cover. Is the sensor facing forward with the connector opening facing forward towards the radiator? I am assembling a LT4 for Glen and thats how his sensor went in. I want to make sure thats correct.

Texas CE

Thanks for the information!

Yep, It is still in the package and yes, it's grease.

The key on my crank is at the 3-3:30 position. I was planning on installing the hub in the same position it came off, with the arrow at the 12:00 position, and it should be okay. My concern is that I may have spun the hub separately from the crank during removal so the above may not be correct. I don't think I did but no key brings up some guesswork.

I think the crank seal was "misting" a little bit but the crank sensor/ harness were soaked in wet oil. Time for a new O-ring!

Texas CE

That's how mine was. I think they can only go in one way due to the bracket.

tjwong

Yes its best to replace that seal now while you have it apart. Also if you rotate your crank so that the opti drive pin is at 9:00 then the crank key should be at about 1:00 then the opti would be firing number 1 cylinder. If you look at the back of the opti you will see markings for either number 1 or 6 cylinder. Make sure its aligned to number 1 if you set the drive pin to 9:00. As there are three slots in the back of the opti drive but the dowel pin only fits in one slot, and that one slot is a different shape than the other two. I have seen people force it on, I am not sure how the do it but its been done, but the car either won't run or runs like crap if its not right. One time beleive this or not. I have seen a cam installed so that the dowel pin either was wrong or it was cut off. The opti was being driven by the three cam bolts which indexed on the three circles on the back of the opti. It too ran like crap

Texas CE

The pin is at the 9:00 but my crank key is at 3-3:30. I have not pulled the timing cover or chain so I am not sure what to make of this.

Do you know the position of the crank keyway relative to the arrow on the hub?

Texas CE

Oops, I took another look and the pin for the Opti is at the 10:00 position so that would put the crank keyway at the 3-3:30 position.

I am thinking I need to rotate the crank 1.75 turns to get the Opti at 9, the crank at 1 and then install the hub at 12. Does this sound right?

bwarren

When I had the hub off my 95, I could see a staining on the end of the hub that matched up with the key way for the crack gear. And there was a staining on the inside of the hub that also matched the non used key way that lines up with the key used for the crank key.

96GS#007

Yep, mine faces forward toward the radiator. In this pic, the sensor is visible.



It's a little difficult to see in the pic above, so here's a link to the large version:

http://forums.corvetteforum.com/phot...k_Complete.jpg

96GS#007

Rotate the crank so the key is at 1 o'clock. Pull the #1 spark plug and use a mechanics mirror and flashlight to verify the #1 piston is at TDC (it better be or you got some other problems to solve ) Once that's verified, install the hub with the arrow at the 12 o'clock position.

Unless you're installing a new timing set (in which case you're setting up the cam in relation to the crank), it simply doesn't matter where the pin on the cam is when you install the opti. When the opti is installed correctly on the pin, it's good to go. As I and Tom mentioned, don't force the Opti in place. Of the three slots on the back of the Opti, 2 are hourglass shapped and one is rectangle shaped. The pin installs in the rectangle shaped slot.

Texas CE

Thanks for the info. I noticed the hourglass on the back of the Opti lined up with the pin. Like you said as long as the pin goes in that hole, the position is irrelevant. I rotated the crank 1.75 times and it is sitting at 1:00, the Opti pin at 9:00 so the hub will go on at 12:00. I think I rotated the hub during removal.

I appreciate the above tips from everyone on the keyway marks!

Happy easter to everyone and their families!

96GS#007

Just to be clear, the cam pin goes in the only slot that is *not* hourglass shaped.

Here is a pic with the hub on. Note the location of the cam pin:



I have an electric water pump, so the water pump driveshaft hole is plugged.

Texas CE

Understand. It is the middle hole between the 2 hour glass shaped holes, it is rectangular shaped and it has a little extra square recess cast above the hole. I appreciate the information!

Another question: When I replace the 3 seals in the timing cover should I install them dry or with a little non-hardening permatex around the outer rings?

96GS#007

I replied to this in your other thread as well Here's what I wrote...

I use a VERY light coat of RTV around the outer edges. It serves as a lubricant such that the seals go in much easier.

It's very important the seals are flat when installed. You can make your own tool using PVC. Here's a pic of the one I made for crankshaft seals:

Texas CE

Excellent! I went to Lowes yesterday and purchased the same seal installer (actually 2, 1 for the crank seal and a larger one for the Opti seal). They only thought they were for plumbing , go figure

Texas CE

I started another thread on the topic of installing a gear drive in place of the timing chain.

Is this workable on the LT1?

Any idea on what mods would be required?

96GS#007

At a minimum you need a new hub, you have to ditch the crankshaft reluctor ring and CPS, and reprogram the computer to account for the deletion of the sensor.

Unless you have plans for some serious racing, I would look no further than the LT4 Extreme Duty timing chain. Pricey, but a very stout piece.

Texas CE

Actually what I have is a Honda 91VFR750 with gear driven cames that make the sweetest sound! I was kinda "what iffing" the Corvette!

The Corvette is stock and I am not planning on racing it. I think the stock chain is fine, does not appear to have much stretch based on watching the Opti pin move as I move the crank back & forth. Since the cover and oil pan are dry I think it's best to button the whole magilla back up and get back on the road!