Stripped!

89avvert · 05-04-04, 02:47 AM

Hi everyone, another new guy here. Just bought my '89 vert a month ago and
went in for an oil change and got a surprise, stripped threads on the oil pan
drain! I have had suggestions to re-tap to a larger plug, good or bad idea? only other option is to replace the oil pan, $500 being the average price. All ideas and suggestions greatly appreciated. TIA

FX GS · 05-04-04, 06:12 AM

At what point in time were the threads stripped? Was everything ok b4 the oil change? Or did the oil change shop cause the problem?

My .03 (raised a penny for inflation) is if retapping the threads for a larger plug solves the problem, go that way. Just make sure that you know the new bolt head size so when you bring the car in for your future oil changes you can tell the shop what size socket to use to remove it.

89avvert · 05-04-04, 08:21 AM

The guy at the shop said the plug had teflon tape or something similar to tighten the fit. The engine had just been rebuilt prior to my buying the car, can't believe they let it out of their shop in that condition.

c4cruiser · 05-04-04, 11:05 AM

There are self-tapping oil pan bolts you can buy but I would worry about getting the threads messed up even more. It sould like the shop that did the motor didn't catch the bunged-up threads or caused it when they replaced the pan and installed the plug.

Milodon should have a replacement pan for an 89. Go to www.summitracing.com and in the part number search box, enter MIL30702 This is for 86-2000 350 car and truck motors and runs $100. You should call Summit Racing and confirm the correct number for a Corvette pan. As far as $500 for a pan replacement, that is steep.

rrubel · 05-04-04, 05:19 PM

If you need a new pan, I'll have a spare in a week or so - switching to an LT1 pan (various reasons) on the new engine so my old pan will be an extra. Off an 86. Make an offer if you're interested...

Yes, I'm trying to free up storage space in the garage

[RICHR]

garycr14 · 05-04-04, 08:46 PM

I would try to retap the hole with a larger size, if it works great, if not your no worse off then you are now. Just keep an eye out for oil drops on the ground beneath the car for a while in case it doesn't work properly.

89avvert · 05-05-04, 01:17 AM

Thanks for the replies. I haven't picked up a shop manual yet, how difficult a job is replacing the oil pan? If I'm going to remove it to re-tap, might as well install a new one. The weather has been great and I got to get it back on the road soon, hopefully this weekend. Thanks again all, been reading your forum the last couple of months and it's good to know there are so many willing to help out.

rrubel · 05-05-04, 06:30 PM

It's not *too* bad. My experience was that you had to remove the starter (to get to a couple bolts) and the shield between the pan and transmission (and if you have an oil cooler then that line has to move). Then it's just a bunch of bolts.
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-=Jeff=- · 05-05-04, 07:22 PM

Quote:

Originally Posted by rrubel

It's not *too* bad. My experience was that you had to remove the starter (to get to a couple bolts) and the shield between the pan and transmission (and if you have an oil cooler then that line has to move). Then it's just a bunch of bolts.
[RICHR]

Actually on the 89.. there are 2 frame supports that need to be removed, they run at 45deg angles from the cradle to the frame on the sides. 4bolts on the ach one.

Then you should be able to drop the pan easily without removing the starter. If you have an oil cooler one line runs under the pan and may have to be removed. I no longer have the oil cooler on mine which makes it easier

rrubel · 05-05-04, 09:04 PM

So there are no longer bolts hidden by the starter? Cool... that was the 2nd hardest part of pulling my pan (first was the oil cooler line, because one bolt would not come out).
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-=Jeff=- · 05-05-04, 10:27 PM

I am pretty sure I left my starter in when I changed the pan gasket..

89avvert · 05-06-04, 01:33 AM

Thanks Jeff and rrubel, sounds like I can save most of $500 and do this myself. I'm going to take a shot at re-tapping the threads, if no luck I'll be checking back with you rrubel on that oil pan.

-=Jeff=- · 05-06-04, 08:35 AM

Rich,

is that spare oil pan for a one piece rear main? I know they chaged at somepoint and the 2pc pan will not work on an 89

rrubel · 05-06-04, 12:27 PM

1-piece. 84 & 85 used the two piece rear main seal. It'll work... just replaced the seal this morning, actually (on the new motor).
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tnovot · 05-06-04, 08:15 PM

Before going off the deep end with an expensive fix, I think I'd check with Napa or GM parts for the availability of an oversized plug.
Such a thing was available back in the 70's and fit the existing threads but just cut them a little deeper. Remember, the threads do not provide the seal - the gasket does.