Motor mount bolts

[JAM1777]

Hi everyone, i recently had someone put a new oil pan gasket on my truck and he couldnt getit to stop leaking cause the pan was warped. So i took the truck back and ordered stock replacement oil pan and new gasket ect. Had to remove motor mount bolts to raise front of motor to slide oil pan out. And noticed one bolt was loose and the other was in crooked not even in right. I was upset that the guy that worked on my truck did work like this and didnt even say anything. So i took the old pan out put the new in and noticed that not only was onebolt loose and one was crooked but also one was a 9/16 and the other was a 5/8 the 9/16 was the loose one and it was stripped. So does anyone know the proper bolt and size are supposed to be used for the motor mounts on a 1969 chevy c10 350 small block??

Thanks for any help

[JAM1777]

As of right now my truck is sitting in driveway with no motor mount bolts in cause i do know what size they are. I figured the 5/8 bolt was thicker with coarse thread so i jacked up the engine from the harmonic balancer and struggled for 2 hours to try to line up the bolt hole on the mount attached to the block to the whole in the bracket on the chassie and could not get the hole to line up on either side. So besides any info on what size the motor mount bolts might be??......... does anyone have any suggestion on how to move the motor around to get the mounts to line up and get bolts in? The engine seems like its sitting about 1/4 inch to far back for holes to line up. And i only have a floor jack. I wish i had a cherry picker handy. Or should i just go buy or rent a cherry picker? Its really been a struggle. Thanks for any feedback

[67 chevelle]

3/8s coarse thread ,inch and a 1/4 long , they generally have a 9/16s head , all I have seen do , it is possible the a 3/8 bolt could have a 5/8 head but it did not come that way from the factory , some engines use a 5/8s head bolt with 7/16s threads for the power steering pump on the front of the engine

[brad_man_72]

Loosen more bolts, engine stands, trans mount. Don't take them all the way out because they won't line up after you get the motor mount bolts in.

[JAM1777]

Thank both of you......i really really apreciate it!

[msgdsrf]

Use a board between your floor jack and the oil pan and lift a little to help move the engine some. Keep all the bolts on the mounts to block and to frame loose until you can finese all the bolts in, then tighten. It was a struggle for me too.

[Tx Firefighter]

They usually use 7/16 bolts (5/8 wrench size head) into the mount and 3/8 bolts (9/16 wrench size head) that hold the mount to the block.

New mounts are way less than 10 dollars each. I'd pull them off the block and look closely at the threaded holes in them. Then, with them in your hand you can assure that you have the proper bolt that screws into it without issue. If the holes are boogered up, get new mounts from any parts store. Then make sure you have bolts that screw into them easily before getting under the truck and fighting with them.

[truckdude239]

you really shouldn;t lift the engine by the balancer can can bent the end of the crank

[JAM1777]

Originally Posted by truckdude239

you really shouldn;t lift the engine by the balancer can can bent the end of the crank

Yeah my friend just said the same thing. So the safest place would be a board and jack under oil pan?

[cdowns]

safest would b a piece of chain lifting with engine crane // and easiest too get everything lined up too/// i second the tought that you should go with new mounts too

[darkhorse970]

Originally Posted by Tx Firefighter

They usually use 7/16 bolts (5/8 wrench size head) into the mount and 3/8 bolts (9/16 wrench size head) that hold the mount to the block.

New mounts are way less than 10 dollars each. I'd pull them off the block and look closely at the threaded holes in them. Then, with them in your hand you can assure that you have the proper bolt that screws into it without issue. If the holes are boogered up, get new mounts from any parts store. Then make sure you have bolts that screw into them easily before getting under the truck and fighting with them.

Good advice, I just went through this while mounting the engine in my '68. I found that one of my brand new mounts had boogered up threads and had to run a 7/16 tap through it to get the bolt through cleanly. I'm not sure if it was a manufacturing defect or a returned part that someone cross threaded, either way the point is to check the mounts while they are out of the truck.

[msgdsrf]

Yup, this too! Thought I was crazy. Had to lift engine and remove mounts to check them out and that's exactly what I found and did. Install went alot better after.

Originally Posted by darkhorse970

Good advice, I just went through this while mounting the engine in my '68. I found that one of my brand new mounts had boogered up threads and had to run a 7/16 tap through it to get the bolt through cleanly. I'm not sure if it was a manufacturing defect or a returned part that someone cross threaded, either way the point is to check the mounts while they are out of the truck.

[JAM1777]

Thanks for all the replies. I got the right bolts and loosened all the brackets and mounts and got the bolts in. Tightened everything down and filled motor oil to level on dipstick and looked under truck and its still leaking from front and back of new oil pan with new fel-pro one piece gasket.

[Lee H]

What pan did you use? Which fel-pro gasket?

OS34510T for '75 thru '85 (thick).
OS34509T for '74 & back (thin).

If you have an upgraded or aftermarket oil pan ... MOST of those use the newer, thick gasket.

Up until 1974 the oil pans used a gasket set with a thin front rubber gasket (rubber seal between pan and timing cover), 1975 and newer and most after market pans use the thick version. The only way to know for sure is to measure the depth by placing a straight edge across the front of the pan. 1 3/16 deep uses the 74 and back thin gasket set, 2 ¼ deep uses the 75 and forward thicker gasket set. Just for reference the Felpro one piece part numbers are: OS34509T for '74 & back, OS34510T for '75 through '85 and most after market pans.