Jump to content

1937 rear main bearing seal


Recommended Posts

Hi,

Greetings from Spain. Last year I bought a 1937 Special Coupe from the US, with engine and transmission completely overhauled some years ago, 7.000 miles on the clock since that was done.  I have all the invoices from that job which unfortunately was poorly done.  After driving the car some 300miles I noticed the occasional knocking from lower end in the engine, pulled out the oil pan and the oil was full of fine metal chips that probably had come off over the year. Main bearing shells showed serious signs of wear (thus the chips) and we decided to take the engine out. What we found was:

- pistons with very little clearance, .0022 to .0025 (2 pistons had seized), pistons pins were almost stuck and not moving freely at all

- all bearing areas on crankshaft showed wear and require regrinding

- all main bearings show wear and can only been thrown into the bin

- no shims were used neither with rod bearings nor with main bearings. Main bearings are .10 undersize

- a modern replacement rear bearing seal was fitted into the groove (wrong for series 40 engines in 1937 I understand)

 

Both rod bearings and main bearings were already converted to insert type. Here's my question: since going back to babbit type bearings is too much of a hassle here in Spain (hardly any shops left who can do that) I will need to go for the next size of insert type mains. Those they sell are all for 1939 and later type of 248" engines I understand. The rear main bearing looks too wide in diameter and probably needs modifying it in oder to not obstruct the oil passage. Attached are 2 pictures showing what I found in my car and how the rear main bearing looked like

 

This thread in the forum from a few years back was already dealing with some of these questions but it would be great if you guys could confirm what I should do best with the rear seal and rear main bearing: no bearing seal and modifying the new bearing to the same look as in the picture (cutting out just a small hole for the oil passage)?

 

thanks

Martin

IMG_20200626_123216.jpg

IMG_20200626_131609.jpg

Link to post
Share on other sites

And here is a picture of a rear main bearing showing how a guy from Australia fixed the situation: using 39 and later shell, cutting off an aprox. 1/8 inch sections of it, modifying that same narrow strip to what you see in the picture and bolting it to the bearing cup. Is this a recommendable way to go for?

20180826_140330.jpg

20180826_140421.jpg

Link to post
Share on other sites

and for the vertical joint behind rear main bearing: should this be sealed off with cork gasket (as per original shop manual from 1937) or modern neoprene replacement? Where to source it? Couldn't see it with Bob Automobilia for example

Link to post
Share on other sites

Not sure what Buick used originally but you can make a wooden square pin and tap it in with some silicone. 

Link to post
Share on other sites
  • 2 weeks later...

"A ball check in the passage between oil collecting groove and the crankcase, prevents oil from running back when the front of the engine is tilted more than 18 degrees equivalent to a 28% grade"

 

Can anyone specify with picture please where the ball should be placed? Which size?

Link to post
Share on other sites
On 7/5/2020 at 5:04 PM, wowo said:

and for the vertical joint behind rear main bearing: should this be sealed off with cork gasket (as per original shop manual from 1937) or modern neoprene replacement? Where to source it? Couldn't see it with Bob Automobilia for example

You may have to buy a rear main seal kit just for the vertical seals and pins(these seal the sides of the rear main cap). s-l1600.jpg

Link to post
Share on other sites
2 hours ago, wowo said:

Can anyone specify with picture please where the ball should be placed? Which size?

The check ball is 3/8"dia(.375). Sorry no picture. It`s been a long time, if i remember correctly, it`s installed in the rear main cap. A roll pin is removed, replace the ball, then reinstall the roll pin.  Maybe someone will correct me if i`m wrong.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...