Oil Pump and, possibly, Rear Main Seal Inspection and Replacement

[Bob Chadwick]

Started to pull the pan to take a look at the oil pump and shaft relating to some rapidly fluctuating oil pressure and a noise coming from the bottom back of the block.

I got the car up on jack stands. But that is as far as I got. How do you get the relay rod connections to come off. A puller? A pickle fork? There didn't seem to be much room between the pieces for a pickle fork so I tried a puller with no luck.

Part of the problem might be that it is a NAPA tool that says "Made in Taiwan" on the side of it. That puppy is going back tomorrow.

Any advice?

 

[80convertible]

If I remember correctly, when I needed to remove the oil pan to replace my rear main seal, I disconnected the idler arm. This allowed me to pull down on the entire steering assembly just enough to gain the clearance necessary to drop the oil pan.

 

[Bob Chadwick]

Thanks Jim. I'll take a look into that. Make it easy on me. Which one of those many steering pieces is the idler arm? :L

 

[80convertible]

Idler arm is on the passenger side...mounts against the frame with 2 bolts. If you have not ever checked it, this would be a good time to check for play in the idler arm. Should not have much movement in the joint. I think my book says 1/4 in or less in any one direction.

 

[Bob Chadwick]

Thanks. Take a look at it tomorrow night. Got to get geared up for the Super Bowl.

I also found a post by Whiplash that encompasses everything that I'm looking at doing.

Thanks Whiplash.

 

[curtis]

Definately good instructions by Whiplash.
Bob, the wildly changing pressure is a good sign of a spun bearing. It's a hassle to fix that. Hope you don't need to.

 

[Bob Chadwick]

Rod or main? Rod doesn't look too hard to change with the pan off, assuming that there isn't other damage that would prevent this. I don't think I would attack a main.

I'm assuming the spinning blocks off the oil galley, which builds pressure causing fluctuation as it spins.

Any reason why it would be intermittent?

A new crate motor is looking more and more attractive.

 

[curtis]

If it is a spun bearing it probably is a main. the fluctuation is caused as you say.Intermittent is because it spins some then hangs then spins again. If scratches in the journal can't be felt with fingernail, just put in the same size bearings, of course if you can feel the scratches, it is time for major work. the mains shouldn't be any harder than rods to change. My machinist says you take off a main cap, then just push the new bearing half under the crank pushing out the old , install new half in cap, set it over crank, tap it on with soft hammer. Do not pull the cap on with the bolts as it will distort the cap. Cap has to be on with same side facing front as it came off.

There is a possibility that the oil pump pickup has come loose and is now too close to the bottom of the pan and that causes cavitation, which will fluctuate your oil pressure. Hope this is the problem.

 

[Bob Chadwick]

Thanks Curtis.

 

[Jack]

Bob:
Very nice and affordable one-piece oil pan gasket is FelPro P/N OS34510T. Comes with all new bolts and works great! If you find a bad main bearing ... and if, IF it has actually "spun" ... check closely the saddle(s)/cap(s) in which bearing shell(s) laid ... if saddle/cap is scored then block needs to come out for "align honing". Same goes for rods/caps. Also, you might wanna first pull the distributor and look at the tang on gear end of it and the slots on top of oil pump intermediate shaft. The tangs/slots can break off/out and give problems you describe. You have to pull oil pump in order to look at bottom tang of int shaft and top slots of oil pump. G'Luck.
JACK:gap

 

[Bob Chadwick]

Jack,

I've got my eye on that gasket. Waiting to get it apart before ordering any parts. The Internet has put the local parts based speed shop out of business having all of the parts. But boy do they get you on shipping.

I've had the distributor out and everything looks good on the top. The noise started when I put the new distributor in and I've got my fingers crossed that I'm going to find that the bottom of the shaft or the plastic ring is damaged.

Thanks for the info on the bearings. Hopefully I won't need it.

Bob

 

[Jack]

Jack, or the plastic ring is damaged.Bob

A different shaft is available from several mfg ... it does NOT have the plastic ring but does have a metal one that is pinned to the shaft ... very affordable & no downside to it. Strongly suggest you upgrade shaft if you drop oil pump.
JACK:gap

 

[Jack]

Bob:
Also, quite common on older motors that the lip of rear main seal wears a very fine groove in crank journal ... and that'll be the root cause of RM Seal leak. Several seal mfg offer a RM Seal that has "offset lip" ... that way the lip rides on a new surface of journal. A new "regular" RM Seal will often seal it up ... but doesn't seal for very long if its lip is riding in a groove. Same thing happens to harmonic balancer snouts.
JACK:gap

 

[Bob Chadwick]

Jack,

As always, a wealth of very helpful info. Thanks.

Bob

 

[Bob Chadwick]

Pan is off. Hardest part was removing the idler arm. Bolts were very close to the headers and a tight fit.

Bottom of pan was clean as a whistle with no metal or shavings of any kind.

I'll post some pictures tomorrow. Anything I should be looking for. Some of the other posts I have read suggest there will be some bluing to the affected cap due to heating if a bearing has spun Is that true because everything looked a nice oil green?

If I understand the oil pump removal it is one bolt in the center of the pump. Anything to be carefully of when taking it out?

I don't think I'm going to even touch my rear main seal. I had some oil on the bottom of the engine but nothing above the pan which suggest to me that the pan was leaking rather than the main seal.

 

[80convertible]

Removing the idler arm bolts are a real pain in the ars. You may want to go ahead and change the rear main seal while you are in there. It's not very difficult or time consuming.

 

[Jack]

Bob:
Since the pan's off, I'd definately change the rear main seal. It's really not hard to do. Just have everything clean & follow directions on seal bag regarding silicone/rtv.
JACK:gap

 

[Bob Chadwick]

Oil pump is out. Looked fine to me. No play or catching when you manipulate the rod or turn it. Doubt that was the problem but for $30 I'll order a new Melling. I've seen a couple of places that sell them with the pickup already welded in place. Will this be acceptable or do you need to position the pickup and tack it into place.

Also, how do you get the rod out? Does it have to be pressed on and off at a shop or do you order the pump with the shaft that has the metal sleeve? I certainly couldn't get it out.

 

[GerryLP]

A word of caution

When installing the oil pump back on, be careful about which torque value you apply on the bolt. Some manuals have a slightly different torque value, and it could prove to be too much. Too much torque will break the area around the hole, and you may need to have the cap repaired at a local machine shop. I used the torque value in my L81 manual, but I forgot that I was using a 1968 short block, so it proved to be too much. Start with 2/3 of the torque value on your manual, and inspect the area around the hole before applying the full torque value.

GerryLP:cool

 

[vette-dude]

Oil pump is out. Looked fine to me. No play or catching when you manipulate the rod or turn it. Doubt that was the problem but for $30 I'll order a new Melling. I've seen a couple of places that sell them with the pickup already welded in place. Will this be acceptable or do you need to position the pickup and tack it into place.

Also, how do you get the rod out? Does it have to be pressed on and off at a shop or do you order the pump with the shaft that has the metal sleeve? I certainly couldn't get it out.

just break the plastic sleeve. Order a new pump drive with the metal sleeve. They just pop over the top of the gear stub on the pump. The plastic sleeves get brittle due to heat and age and eventually break. The new pumps usually come with a new plastic sleeve but I don't recommend you bother with it. The Steel sleeved drives are really inexpensive insurance.

Randy

PS: The pump does look worn to me on the gear teeth and the end plate which are critical areas for these pumps. I also replace the bolt with a stud and nut made for this application.