Oil Leak, Is That Hole Supposed to be there? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1968CHEVYC10 · 06-23-2010, 01:48 PM

I recently got my truck running. last Sunday I changed the oil and since I've been noticing some oil leaks (it may have been leaking before but I never checked). looks like there is a small leak around the oil pan seal next to the harmonic balancer, but the one that has me worried is on the bellhousing/clutchhousing (don't know which term is correct, it's a manual) coming out of a hole on the bottom. I don't think the bellhousing is supposed to be full of oil and it doesn't look like it based on the amount of oil that's coming out (just a drop) so I'm thinking the leak is inside there and coming from the engine. Anyway there is this hole on the bottom of the bellhousing where the oil is dripping and I'm wondering if the hole is supposed to be there or if there would be a problem if I plugged it. Anyway here's some pics, tell me what yall think.

I tried to edit it on paint but it didn't work, you can see a line of oil coming from the hole.

The hole is probably about 1/4"

parked the truck here yesterday evening, so this puddle formed in about 18 hours or so. When the motor is running you can see a drip about every 3 seconds.

stealthy '69 · 06-23-2010, 01:54 PM

Yes that hole is supposed to be in the bottom of the the clutch dust shield (at least that's what i call it). It's to drain any moisture and keep it from getting on the clutch disk. My best guess is the oil is coming from the rear main seal and running down into the dust shield. Just my opinion though.

beebster · 06-24-2010, 01:00 AM

Quote:

Originally Posted by stealthy '69

Yes that hole is supposed to be in the bottom of the the clutch dust shield (at least that's what i call it). It's to drain any moisture and keep it from getting on the clutch disk. My best guess is the oil is coming from the rear main seal and running down into the dust shield. Just my opinion though.

Good call stealthy'69 and hoppa, rear main seal sounds about right.
Distributor gasket is the other possibility. Such a small gasket but it can make a big mess.

stealthy '69 · 06-24-2010, 08:32 PM

Quote:

Originally Posted by beebster

Good call stealthy'69 and hoppa, rear main seal sounds about right.
Distributor gasket is the other possibility. Such a small gasket but it can make a big mess.

good point. now that you mention it i had an s-10 in high school that had the same issue.

hoppa · 06-23-2010, 01:54 PM

Yeah the hole is supposed to be there to drain oil when your rear main is leaking lol...Sorry for the bad news but that is more than likely what it is IMO, it can be done in truck with lifting the motor and dropping the pan/rear main. Don't forget to stagger and dab of silicone on the ends.

hoppa · 06-23-2010, 01:55 PM

Wow look at the post times lol

stealthy '69 · 06-23-2010, 01:55 PM

I guess great minds think alike, don't they hoppa

hayhauler71 · 06-23-2010, 09:09 PM

I would clean the backside of the intake and start it up and check for the leak. Possible dizzy gasket or oil pressure line [sender] on back of intake is very common.

hoppa · 06-23-2010, 09:35 PM

Yeah for sure check the simple stuff first...the rear main inframe is not fun.

Dynomutt · 06-23-2010, 10:44 PM

If the truck has been sitting for a while, and has cork gaskets, the gaskets will dry up and shrink. It could be leaking around the back of the oil pan. You might try "snugging up" the oil pan bolts and it may stop some of the leaking. You have to be careful doing this though because if the gasket is real bad it could make the leak worse. I agree that it looks like it may be a rear seal though. That seal will also dry and crack if it's been sitting with no oil on it for a while. Again, just one man's opinion.

GASoline71 · 06-24-2010, 08:35 PM

If you say it is leaking pretty steady when the engine is running... and it's dripping out of that hole... I'm betting it's a rear main seal.

Gary

**leddzepp** · 06-24-2010, 08:43 PM

I will also bet it is the rear main seal, and your timing cover seal is probably also leaking.

trusty72 · 06-24-2010, 10:11 PM

yip sorry probably rear main. its not that bad though, drop the pan and roll a new one in. go with a nice one piece oil pan gasket when u go back with it, worth its weight in gold.

1968CHEVYC10 · 06-24-2010, 10:12 PM

Thanks for the help yall. If I replace the rear main seal does this mean need to replace the entire oil pan gasket?

**leddzepp** · 06-24-2010, 10:17 PM

I would replace the entire oil pan gasket with a Fel-Pro one piece rubber seal. Costs more money, but it is worth it. They are also re-useable. Mine was $60 for my BBC. Cork is porous and will eventually leak again.

msgross · 06-24-2010, 10:18 PM

yep, you need to remove the entire pan, remove the rear crank cap and replace the seal... cheap fix but not fun if you've never done it before. Do some research first... plan on a 1/2 day. You'll have to remove the engine mount bolts and lift the engine a few inches.

I did this on my project flip this truck build and it stopped all the leaks. You just wasted the oil that you put in though, unless you try to reuse it...

71GMCer · 06-24-2010, 10:37 PM

I just did this job myself and Most likely you will have to get new oil. Depending on how much sludge is in the bottom of the pan ( I had about 1/4 of an inch of sludge so new oil definately was needed!)

I suggest Fel-Pro gaskets and definatley check the back of the intake and oil pressure sending unit.

Matt

LONGHAIR · 06-25-2010, 06:49 AM

I'm on the rear main seal badwagon too. The other potential leaks that were pointed out are just as likely to exist, but in reality they they would leak on the outside of the bell housing. The leak from the inside, rear main seal.

GASoline71 · 06-26-2010, 12:53 AM

Quote:

Originally Posted by LONGHAIR

I'm on the rear main seal badwagon too. The other potential leaks that were pointed out are just as likely to exist, but in reality they they would leak on the outside of the bell housing. The leak from the inside, rear main seal.

That's where I concluded rear main seal as well.

Another vote for the Fel-pro one piece oil pan gasket. Just make sure you get the one with the proper thickness for where the oil pan meets the timing chain cover.

Gary

1968CHEVYC10 · 06-25-2010, 09:03 PM

I checked the distributor gasket because I replaced the dizzy recently and it was fine, I'll check the Oil pressure line when I get a chance, but based on yall's replies I'm pretty sure it's the rear main. Is the timing cover on the rear of the engine? And what about the crank cap? not sure what that is. Thanks again yall, really appreciate it!

gkesseru · 06-25-2010, 10:06 PM

The timing cover is on the front of the engine. It usually leaks around the harmonic balancer. He's just saying that the front of the engine usually leaks also. If you pull the balancer look for a groove caused by the seal. You can fix that with a tube that slips over the balancer shaft.
The crank cap is the rear main crankshaft bearing cap that you will need to remove once you get the oil pan off.

1968CHEVYC10 · 06-25-2010, 11:51 PM

Quote:

Originally Posted by gkesseru

The timing cover is on the front of the engine. It usually leaks around the harmonic balancer. He's just saying that the front of the engine usually leaks also. If you pull the balancer look for a groove caused by the seal. You can fix that with a tube that slips over the balancer shaft.
The crank cap is the rear main crankshaft bearing cap that you will need to remove once you get the oil pan off.

Awesome thanks, So I need to replace these gaskets also?

JimmyFloyd · 06-25-2010, 10:17 PM

From the title of this thread, I thought it was going to be something about BP...

**leddzepp** · 06-26-2010, 02:55 AM

Your timing cover seal will be easy to replace with a seal puller, or if careful, a screwdriver to pry it out. You first need a harmonic balance puller/installer to remove it from the crankshaft in order to remove the timing cover. You can use the "loan" program at auto zone or kragens for the tool. You leave a deposit, upon return of the tool, you receive your deposit back, so it's free.

409impala1 · 06-26-2010, 10:28 AM

muffler bearing, ok as it needs a lot of lubrication..

06-23-2010, 01:48 PM	#1
1968CHEVYC10 Registered User Join Date: Aug 2009 Location: Tomball, TX Posts: 578	Oil Leak, Is That Hole Supposed to be there? I recently got my truck running. last Sunday I changed the oil and since I've been noticing some oil leaks (it may have been leaking before but I never checked). looks like there is a small leak around the oil pan seal next to the harmonic balancer, but the one that has me worried is on the bellhousing/clutchhousing (don't know which term is correct, it's a manual) coming out of a hole on the bottom. I don't think the bellhousing is supposed to be full of oil and it doesn't look like it based on the amount of oil that's coming out (just a drop) so I'm thinking the leak is inside there and coming from the engine. Anyway there is this hole on the bottom of the bellhousing where the oil is dripping and I'm wondering if the hole is supposed to be there or if there would be a problem if I plugged it. Anyway here's some pics, tell me what yall think. I tried to edit it on paint but it didn't work, you can see a line of oil coming from the hole. The hole is probably about 1/4" parked the truck here yesterday evening, so this puddle formed in about 18 hours or so. When the motor is running you can see a drip about every 3 seconds. __________________ '68 C10 LWB 6.2NA/NP833 3.73's

06-23-2010, 01:54 PM	#5
hoppa Registered User Join Date: Jun 2010 Location: Midlothian TX Posts: 56	Re: Oil Leak, Is That Hole Supposed to be there? Yeah the hole is supposed to be there to drain oil when your rear main is leaking lol...Sorry for the bad news but that is more than likely what it is IMO, it can be done in truck with lifting the motor and dropping the pan/rear main. Don't forget to stagger and dab of silicone on the ends. __________________ 69 SWB 505 bbc 86 GMC SWB 406 sbc 86 G20 camper cruiser van 1984 Chevy C30 Ramp truck

06-23-2010, 01:55 PM	#6
hoppa Registered User Join Date: Jun 2010 Location: Midlothian TX Posts: 56	Re: Oil Leak, Is That Hole Supposed to be there? Wow look at the post times lol __________________ 69 SWB 505 bbc 86 GMC SWB 406 sbc 86 G20 camper cruiser van 1984 Chevy C30 Ramp truck

06-23-2010, 09:09 PM	#8
hayhauler71 Registered User Join Date: Aug 2009 Location: St. Paul MN. Posts: 1,996	Re: Oil Leak, Is That Hole Supposed to be there? I would clean the backside of the intake and start it up and check for the leak. Possible dizzy gasket or oil pressure line [sender] on back of intake is very common.

06-23-2010, 09:35 PM	#9
hoppa Registered User Join Date: Jun 2010 Location: Midlothian TX Posts: 56	Re: Oil Leak, Is That Hole Supposed to be there? Yeah for sure check the simple stuff first...the rear main inframe is not fun. __________________ 69 SWB 505 bbc 86 GMC SWB 406 sbc 86 G20 camper cruiser van 1984 Chevy C30 Ramp truck

06-23-2010, 10:44 PM	#10
Dynomutt Registered User Join Date: Mar 2009 Location: North Texas Posts: 440	Re: Oil Leak, Is That Hole Supposed to be there? If the truck has been sitting for a while, and has cork gaskets, the gaskets will dry up and shrink. It could be leaking around the back of the oil pan. You might try "snugging up" the oil pan bolts and it may stop some of the leaking. You have to be careful doing this though because if the gasket is real bad it could make the leak worse. I agree that it looks like it may be a rear seal though. That seal will also dry and crack if it's been sitting with no oil on it for a while. Again, just one man's opinion. __________________ MARQ Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=446194

06-24-2010, 08:43 PM	#12
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,004	Re: Oil Leak, Is That Hole Supposed to be there? I will also bet it is the rear main seal, and your timing cover seal is probably also leaking. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man

06-24-2010, 10:11 PM	#13
trusty72 Registered User Join Date: May 2010 Location: ft smith arkansas Posts: 131	Re: Oil Leak, Is That Hole Supposed to be there? yip sorry probably rear main. its not that bad though, drop the pan and roll a new one in. go with a nice one piece oil pan gasket when u go back with it, worth its weight in gold. __________________ 1972 super cheyenne 1970 Suburb

06-24-2010, 10:12 PM	#14
1968CHEVYC10 Registered User Join Date: Aug 2009 Location: Tomball, TX Posts: 578	Re: Oil Leak, Is That Hole Supposed to be there? Thanks for the help yall. If I replace the rear main seal does this mean need to replace the entire oil pan gasket? __________________ '68 C10 LWB 6.2NA/NP833 3.73's

06-24-2010, 10:17 PM	#15
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,004	Re: Oil Leak, Is That Hole Supposed to be there? I would replace the entire oil pan gasket with a Fel-Pro one piece rubber seal. Costs more money, but it is worth it. They are also re-useable. Mine was $60 for my BBC. Cork is porous and will eventually leak again. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man Last edited by leddzepp; 06-24-2010 at 10:18 PM.

06-24-2010, 10:18 PM	#16
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: Oil Leak, Is That Hole Supposed to be there? yep, you need to remove the entire pan, remove the rear crank cap and replace the seal... cheap fix but not fun if you've never done it before. Do some research first... plan on a 1/2 day. You'll have to remove the engine mount bolts and lift the engine a few inches. I did this on my project flip this truck build and it stopped all the leaks. You just wasted the oil that you put in though, unless you try to reuse it... __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer"

06-24-2010, 10:37 PM	#17
71GMCer Registered User Join Date: Apr 2010 Location: Kelowna, Canada Posts: 116	Re: Oil Leak, Is That Hole Supposed to be there? I just did this job myself and Most likely you will have to get new oil. Depending on how much sludge is in the bottom of the pan ( I had about 1/4 of an inch of sludge so new oil definately was needed!) I suggest Fel-Pro gaskets and definatley check the back of the intake and oil pressure sending unit. Matt __________________ 1970 GMC 1/2 Ton 4x4 350sbc SM465 NP205

06-25-2010, 09:03 PM	#20
1968CHEVYC10 Registered User Join Date: Aug 2009 Location: Tomball, TX Posts: 578	Re: Oil Leak, Is That Hole Supposed to be there? I checked the distributor gasket because I replaced the dizzy recently and it was fine, I'll check the Oil pressure line when I get a chance, but based on yall's replies I'm pretty sure it's the rear main. Is the timing cover on the rear of the engine? And what about the crank cap? not sure what that is. Thanks again yall, really appreciate it! __________________ '68 C10 LWB 6.2NA/NP833 3.73's

06-25-2010, 10:06 PM	#21
gkesseru Registered User Join Date: Dec 2009 Location: California, Maryland Posts: 544	Re: Oil Leak, Is That Hole Supposed to be there? The timing cover is on the front of the engine. It usually leaks around the harmonic balancer. He's just saying that the front of the engine usually leaks also. If you pull the balancer look for a groove caused by the seal. You can fix that with a tube that slips over the balancer shaft. The crank cap is the rear main crankshaft bearing cap that you will need to remove once you get the oil pan off. __________________ 72 Fleet (died) 78 Step (sold) 55 Step named Fred (sold) 00 F150 68 Step (named El Scorcho by PO) Build thread for the new El Scorcho http://67-72chevytrucks.com/vboard/s...d.php?t=392932

06-25-2010, 10:17 PM	#23
JimmyFloyd Registered User Join Date: Apr 2009 Location: Rochester, NY Posts: 1,458	Re: Oil Leak, Is That Hole Supposed to be there? From the title of this thread, I thought it was going to be something about BP... __________________ 1970 Blazer 350/SM465/205 SOLD! \| 1998 Z3



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06-26-2010, 02:55 AM	#24
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,004	Re: Oil Leak, Is That Hole Supposed to be there? Your timing cover seal will be easy to replace with a seal puller, or if careful, a screwdriver to pry it out. You first need a harmonic balance puller/installer to remove it from the crankshaft in order to remove the timing cover. You can use the "loan" program at auto zone or kragens for the tool. You leave a deposit, upon return of the tool, you receive your deposit back, so it's free.

06-26-2010, 10:28 AM	#25
409impala1 Registered User Join Date: Dec 2005 Location: nebraska Posts: 136	Re: Oil Leak, Is That Hole Supposed to be there? muffler bearing, ok as it needs a lot of lubrication..

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