The Stovebolt Site Forums The Shop Area Engine Shop Front Plate Leak

My front plate is leaking on my 216. I know the cam and crank have to come out since the gears are pressed on. I am a novice at engie repair work. Can this be done at home? I have replaced the head gasket, rebuilt carbs, set valve lash, and tuned it up with no issue in the past. Don't know how much skill it takes to take the insides apart and put back again. Can it be done by a amature?

An oil leak at the front of the engine is 99% of the time a leak from the front crankshaft seal in the timing cover. You may also have a little seepage from the timing cover gasket.
To repair this, the harmonic balancer has to be pulled. This has to be done with a pulley puller that is bolted to the center hub on the balancer to keep from damaging the balancer.
Then the timing cover can be removed and a new seal installed. If inspection of the crankshaft-sealing surface shows any wear (which it probably will) an offset seal might work or if it is to badly worn a wear sleeve or “Speedi-Sleeve” can be installed.
To gain access to the lower front of the engine the radiator will need to be removed and even then it is difficult to get at the balancer. Unless there is a problem with the timing gears there is no need to remove them to fix a front oil leak.
Denny Graham
Sandwich, IL

Thanks Denny but I did all of that stuff when I had it apart. The balancer was sleeved, the timing cover has a new gasket and a new seal where the balancer rides, an a new oil pan gasket was installed. I even re-tighten the bolts and the leak is still there. It is driving me crazy!!! Any suggestions?? I did use the original srews in the timing cover. I was thinking about getting bolts because I figured they would torque better but didn't. Think that may be the issue?

Okey Dokey, ya'll lead me to believe that "Don't know how much skill it takes to take the insides apart and put back again. Can it be done by a amature?" In that case, bout the only thing that comes to mind is if you tightened up the timing cover and didn't use a centering sleeve the cover might be off center a tad, which could make the seal leak. Ya sure it's not the front oil pan gasket that's leaking, they can be a bear to get in correctly???
DG

You have to figure out where it is coming from. If you have a leak between the front cover and the front plate it can be stopped by cleaning it well and applying some RTV. I had to do this on mine and I had to remove the balancer to do it. This same procedure can be used for a leak between the plate and the block, which would appear on the rear surface of the front plate. Oil that is not under pressure can be stopped with an external fix.

I guess my reply didn't really cover the issue here. Taking out the crank and or camshaft have absolutely nothing to do with fixing an oil leak. In addition it is not required to remove either gear to remove the crankshaft or camshaft.

Denny -

You mentioned "an offset seal" could be installed in the timing cover. Just what is an offset seal? I'm not familiar with that term.

Thanks,
Joe

The lip of the seal is offset from its normal contact point so it seals against a different part of the balancer sealing surface. How ever that is a mute point since he said he already have installed a Speedi-Sleeve. I'm not even sure if you can find them anymore Joe, but it doesn't hurt to look or ask. Chicago Rawhide might still make them.
Denny G

Where I live, CarQuest carries an offset seal. Also I found that the conventional seal from Carquest had the normal sealing lip but the one from NAPA had an inner and an outer seal.

A quote from the 1948-1951 Chevrolet truck shop manual in bold type:


“Note: It is important that the centering gauge be used to align the timing gear cover so that the harmonic balancer installation will not damage the seal and to provide uniform seal tension on the hub of the balancer.”

I read this as the seal needs to be held in a position concentric to the crankshaft when the bolts are tightened to function as designed. An old balancer with the bore polished out a bit to slip on makes a perfect cover alignment tool. It’s #17 on this page and IMO skipping this step is asking for a leak:


http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0646.htm

That’s interesting Fred, it would be nice to know who was making those seals for CarQuest and NAPA.
That's correct Curt, that's what I said yesterday morning. Thanks for posting the link to the page. That’s when a little lathe comes in handy.
Denny Graham
Sandwich, IL

Can you get me the part number off of the NAPA one so I can give it to the guys here in Indiana. They don't know what I am talking about!

Thanks for all of the replys guys! I have been off line for awhile and just got back on.

Not 100% sure it isn't the pan gasket. Could very well be. I think this week end I am going to drop the pan and pull the timing cover off again and re-gasket them both one more time. I didn't know about the centering sleeve. Thant may be my problem!!! I wish someone would make a one piece oil pan gasket for these engines.

I'm in the process of assembling a 235. What are you guys using as a centering tool for the timing cover? I don't have a lathe. thanks

It seems to me that with a little bit of measuring you could size a piece of PVC pipe to make a centering tool.

We normally use the pulley itself. The hard part is getting the bolts tightened up in the area of the pulley.

If by chance the harmonic balancer has a damaged area where the seal rides, I prefer to use a Felpro Speedi-sleeve (NAPA sells them..$8.00) that slides over the damaged area (no machining needed) and is held on with an epoxy adhesive. This provides the stock seal with a "new" contact surface.

I've found that sliding the LOOSE timing cover (with new stock seal) over the renewed seal surface of the balancer CENTERS the seal surface. Once the balancer is seated fully on the crankshaft, you can tighten up the timing cover bolts. This guarantees that the seal is centered on the HB. The HB installation process is made much easier if you drill/tap the crank snout to use a SBC balancer bolt with a couple washers/bearings to PRESS the HB home.

Drilling/tapping the crank on a 235 with a battery powered drill isn't at all complicated as the snout has a cone shaped surface inside to insure centering. Being able to press the HB into place and tightening the timing cover AFTER, eliminates any potential for this pesky seal leak. It takes a whole lot less time to drill and tap than to have to replace a leaking seal, and eliminates having to use a BFH.

Dave

drilling and tapping the crank sounds like a good idea. What size drill, tap and bolt do I need to get.Thanks

The Small Block Chevy balancer bolt is a 7/16 X 20 thread and the correct drill is 25/64ths. I drill my pilot holes about 9/16" deep so I don't get into the oil passages in the crank.

By drilling/tapping you can use a standard Harmonic balancer installation tool to press/draw the balancer home. I would not recommend trying to use the balancer bolt itself and torque to force the balancer home. You just don't have enough threads to take the force. A balancer installation set is available from AutoZone and other FLAPS. You place a deposit on the tool and get a 100% refund when you return it.

The installation kit contains a couple bearings...the center stud screws into the threads you cut for a purchase....and then you spin the nut down against the bearings. The center stud doesn't turn during the process so you won't have to worry about boogering up the threads you cut. When you get the balancer with the loose (seal centered) timing cover, I'd start the timing cover bolts in the block and gradually tighten them as you seated the balancer. I like to use rvt (sparingly) to glue the gasket to the timing cover and then after the rvt has cured, use #2 Permatex where it seals against the block.

On the 235 block, the 2 bottom timing cover bolts are removed/installed with the pan removed to get the cover on or off. This is a real hassle and if your engine is torn down, it's an easy fix to thread the front main journal with 3/8" threads and drill out the holes in the block and cover so you can just install all the timing cover bolts from the front of the block. Should you ever need to pull the timing cover it eliminates having to drop the oil pan.

If you have questions send me a PM.

Dave

"On the 235 block, the 2 bottom timing cover bolts are removed/installed with the pan removed to get the cover on or off. This is a real hassle and if your engine is torn down, it's an easy fix to thread the front main journal with 3/8" threads and drill out the holes in the block and cover so you can just install all the timing cover bolts from the front of the block. Should you ever need to pull the timing cover it eliminates having to drop the oil pan."

Just wanted to reinforce this suggestion , as its valid for the 216 also.

I've got a question Dave. I'm looking at a Moroso installer tool and it looks like a large fine thread (3/4" to 1") thread shaft that is tapped in the end to take a variety of different studs. In this case a 7/16"-20 thread is attached to the shaft and the assembly is tightened into the crank with a hex head on the outer end of the shaft. There appears to be a spacer sleeve, I assume to go over the drive dog for the hand crank and a thrust bearing that’s driven by a large nut. So is that all there is to it??
This makes a whole bunch of sense when you compare it to beating the balancer on with a sledgehammer. Why haven't I ever seen one of these kits before? The kits appear to be about $35 or $40 at most stores and would be worth it for anyone doing any amount of engine work.

It doesn't sit right with me putting the old balancer back on without having it reconditioned. That vulcanized rubber is 60 years old and is probably as hard as a rock by now. So there is no way that it can do its intended job correctly. That may just account for some of that vibration we get from the engine when it’s up to speed. Pressing the damper on with one of those tools certainly looks like a grand idea to me.

Since I just happen to have the front end off of mine this week for some other work, I figured it would be a good time to service the front seal and damper. I’m going to make a sleeve up on the lathe that will serve a dual purpose, one to slip over the crank nose and center up the seal and two as a guide for the drill. In the end I’m going to insert a drill bushing to keep the tap drill in line with the crank and if I plan it right it could also be used to guide the tap when starting it.

Denny Graham
Sandwich, IL

Denny, my balancer is sans the crank dogs so it was a none issue. However, it would be easy enough to use a short piece of pipe and a flat washer to give you the clearance you'd need to draw the HB home. As for centering the drill in the crank...my 235's were internally tapered so the drill bit centered itself. I would suggest using a smaller bit for the initial hole....easier to control and makes less work for your 25/64's bit. The installation kit is worth every penny and with the interchangeable tips it's already paid for itself.

I agree totally that it's a wise move to spring for a new balancer. If you've come to love your old balancer (no pun intended) a trip to the Balancer Doctor might be just the ticket. IMO having to change the timing cover seal ($5.00) is one of the biggest PIA fixes on the whole truck. Seems like you have to pull everything mechanical except the tailgate to get room to work!!!! That's why I take the time to wrestle with the timing cover loose, with the seal surface centered on the balancer, and ease it into place. Adding the Felpro Speedi-sleeve to any but a new balancer is SOP. Even a slight weep from the front seal will be blown back over the entire engine and serve as a crud magnet. There's no reason for a 216-261 engine not to be as dry as a bone....even with the down-draft tube.

I wouldn't concern myself too much on the drilling and tapping process. The cranks I've done have drilled like butter and taken a clean thread. I'd make sure that my drill bit was properly sharpened and the tap wasn't high mileage.

It looks like you've set yourself up with a number of operations you can do while she's free of the sheet metal. That's the neat thing about these old Chevy girls; you could put it all back together and drive it tomorrow or spend a month having fun making her fit and perform better than she did when new!!! Ain't old iron great????

Dave

GRRRRRReat! Just park next to one of those new Mustangs some day at a car show, what a compairison. It would take you three days to change the plugs in one of those, if you could find them under all that crap.
DG

I have been keeping track of this thread hoping someone will post the PART NUMBER for either a Carquest, NAPA, Fel-Pro, Victor, Chicago Rawhide or any manufacturer's OFFSET SEAL for the front timing cover of a 216-235-261 engine. An OFFSET SEAL is a much more appealing solution to the leakage problem than a Speedi Sleeve. For some reason, I feel the OFFSET SEAL would be a longer lasting fix for the problem.
Thank you to anyone and everyone that can supply a Part Number.

Wouldn't mind finding a source myself Joe. I know I used to sell them back a hundred years ago when I was a parts man but I've no idea where you can find them now. It’s a new world we live in today where you buy a car and very rarely have to open the hood during its life. Mostly electronics that goes bad on them today.
I would disagree with you about the Speedi-Sleeve being a temporary fix. I think that they are a grand idea and wouldn't hesitate to use one on any sealing surface. If it’s the fact that they use an adhesive that bothers you, I wouldn’t worry bout that, I’m sure it’s compounded to take the temperature and oil.

Interesting reading from SKF: http://www.skf.com/files/774717.pdf

Also your Speedi-Sleeve pn. is CR 99176 for the Standard sleeve and CR 99829 for the Gold sleeve.
Denny Graham
Sandwich, IL

Hi Joe,

The Speedi-sleeve is not the solution to timing cover seal leaks. It's USING THE PROPER INSTALLATION PROCESS. Centering the loose timing cover/seal on the HB snout before you draw it (HB) down and tightening the timing cover bolts, insures that you'll have equal pressure around all the seal surface. Smooth seal surface+centered seal=no leaks.

As for adding a Speedi-sleeve; rarely will you find a 50 year old balancer that doesn't have some tracks worn in the seal surface area. A fresh seal on a worn balancer snout is just prolonging a leak. The sleeve gives you a perfectly smooth surface. A new sleeve with an HB drawn down on a bolted down timing cover may or may not center the seal on the HB. Taking a little extra time to install the HB/timing cover correctly will eliminate the need for an illusive "OFFSET SEAL" and save you from how to figure out exactly where to locate the illusive "OFFSET" seal in the timing cover.

Dave

Thank for the information, Guys, but I am still interested in find out what the part number is for an OFFSET timing cover seal. I'm not stubborn, I just need the part number.
Thanks!

Me too! Let me know if any one ever post the part number for this bad boy. I am inclined to think that it doesn't exist.