: Broken Oil Pan Bolt... What now?

08-12-2010, 06:30 AM
Hi guys, I'm really hoping for some advice here as I'm dumbfounded how this actually happened. I usually just lurk but today I finally felt the need to post... what an introduction. Right to the point...

Got an 04 GTO and was putting in a cam and upgrading the timing chain. One of the rear oil pan bolts broke as we tightened it back up. We followed torque specs and torqued it to 5 ft first, which something seemed slightly off, and then 9... and snap.

Part of the bolt broke off in the block. The good news is that I think that part of the bolt is sticking out of the block. Bad news is I have to completely remove the oil pain.

What we plan to do is just pull the engine... seems like there will be less problems with reassembly than dropping the cradle.

So a couple questions...

1) Does anyone have part numbers for these bolts?

2) What are my options if the bolt that broke off is not protruding from the block like I am suspecting...?

3) Does this bolt go bad often? The other one seem to tighten correctly with no problems what so ever.


Place where bolt goes:


08-12-2010, 06:45 AM
Was going to say drill it out and Tap it but it looks to long to get a drillbit in there. Can you get an easy out in there? Would say put it on a lift to save pulling everything out.

08-12-2010, 06:55 AM
It is actually on my buddy's lift right now. We just don't want to mess with power steering lines, cradle alignments, and all the other junk in the way when pulling the engine at this point is just dropping the tranny and the engine mounts.

The plan is to take the pan off completely, and hope to god that the remaining bolt is protruding out of the block. Enough that we could grip it or weld something to it.

08-12-2010, 07:11 AM
Would try tig welding something on it like you said if someone is good with it. If that doesnt work the I would drill into it and use an easy out. Was it just the head that broke off?

08-12-2010, 07:22 AM
The bolt is like a very long bolt. The head is still on, if that was the part that broke off I'd be much happier as I'd be sure I could pull it out.

Anyway, the bolt is a pretty long bolt as picture, and probably is missing about an inch. Looks like mocking it up to the pan that there may be 1/4 of an inch protruding from the block... hopefully.

I really don't want to drill into the block, but if thats what needs to happen, so be it.

08-12-2010, 07:25 AM

The rear side bolt broke. As you can see it is a long bolt that pretty much slips through 5" of the oil pain and then mounts to the block. So the oil pan needs to be dropped.

Anyone have these bolts break before?

08-12-2010, 07:44 AM
Just ordered an ARP bolt set. We'll see how that all works out.

08-12-2010, 07:48 AM
I've had some success in the past with broken bolts like this that use low torque by pushing on the head hard with the socket as I try to take it out. Sometimes that pressure is just enough to get the broken part backed out.

08-12-2010, 07:53 AM
Great idea, I will give that a shot.

08-12-2010, 08:33 AM
by the looks of it, it doesnt look like any of the bolt will be out of the block to grab. I think an easy out will be your best bet. worse comes to worse just drill it out and re tap the hole, or use a helicoil

JoeMama's GTO
08-12-2010, 02:41 PM
I've had some success in the past with broken bolts like this that use low torque by pushing on the head hard with the socket as I try to take it out. Sometimes that pressure is just enough to get the broken part backed out.

TRY this first before any welding/easyouting/drilling. There is no tension on the threads until the head of the bolt is flush with the pan. You should be able to get it out with just your hand.

08-13-2010, 05:52 AM
these bolts do not go into the block, but the rear cover

I think your best option is to pull the trans and flywheel so you can get to the rear cover. remove cover and work on getting your broken piece out of the cover on the bench.

If you drop the pan/cradle then you still will be trying to get up in there to get at the bolt piece with the flywheel in the way.

These 2 long bolts get torqued to INCH/LBS by the way, not Ft/LBS

08-13-2010, 01:25 PM
9 ft lbs is right. (9 x 12 = 108 in lbs so close enough). Definitely don't torque it to 106 ft lbs HAHA

08-13-2010, 06:13 PM
I'm a little curious....

Why did you have any reason to mess with that bolt....while doing a cam change??? There shoulda been no reason to drop the pan....

Probably...if you can remove the pan (now), you'd be able to screw out the broken piece by hand...with a scribe. (Assuming it was broken by over-torquing it. If it seized and broke off that's different)

08-18-2010, 01:05 PM
We were changing the timing chain out.

Anyway, we found out the cause and fixed it with a set of ARP oil pan bolts.

The bolt was cast wrong from the factory. There was a bubble in the casting that was probably in trouble from the first time it was installed. A little more from removing it, and finally snapped while reinstalling it.

The oil pan had to come off to get it, and as I thought from mocking up the bolt, it was sticking slightly out of the engine. You can see it in this picture...

So I had a friend who has been in the failure analysis business for some time take a look at the bolt. He immediately pointed out that the dark spot that covers much of the center is a casting flaw. That there must have been some dirt in there or something because it would never had been that dark if it just broke off from too much torque. It would have been shiny.

As you can see from the below picture that the only shiny parts of the bolt were around the edges. This bolt was bad from the beginning.


I guess it happens.... just a pain in the ass.

BTW, the remaining bit that was in the engine came out by hand. Wouldn't come out pressing the longer bolt in and turning though :/

08-18-2010, 01:57 PM
Ok I know its after the fact but why did you even touch that bolt? I have done two cams and oil pumps and never touched the pan bolts except the ones going in the front cover.