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#1 |
Registered User
Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 33
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1970 Chevrolet C20 Pickup - Motor Leaking Oil
I have a 1970 Chevrolet C20 350, 5.7 pickup truck. The motor is leaking oil. I am trying to get an idea of possible places were the motor is leaking oil and what is required to fix it.
If I was to clean the motor to have a clean motor and look for oil leakage, what is typically used to clean the motor? Also, what parts need to be covered if water is used? What are the places the motor would leak oil? Valve cover gaskets and head gaskets? Any other places? What is typically done to fix motor oil leakage? Replace valve cover gaskets? head gaskets? Anything else? Might it require removal of motor? Just trying to be well informed as I look for a mechanic or mechanic shop. Appreciate the help. |
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#2 |
Senior Member
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Location: TN.
Posts: 8,119
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
I would start with cardboard placed under the Engine.
Then you can see a local point of the Major Leak. There are lots of cleaners and processes. Simple green or Purple power work. A person just has to be cautious about spraying on Wiring and electrical stuff.
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________________________________________________________________________________________ ____________________________________________ 84 Chevy K-20 63 Impala (my high school car) http://67-72chevytrucks.com/vboard/s...Crew Cab Build |
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#3 |
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Location: Portland Oregon
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Any ideas on the age or mileage on the motor? On high mileage motors any gasket may be leaking. Cheap gaskets will fall before quality gaskets will. And any gasket can fail if improperly installed.
Common points that leak but don't cause other problems (Like a leaking head gasket may) The front and rear intake manifold gaskets. Rear main seal. Oil pan gasket. Front main seal. Fuel pump. Valve covers. This can be from bent or deformed covers as well gasket failure. There are more but these are the most common ones I've seen over the years. Replacing the PVC valve and hose can help as a collapsed hose or stuck valve can allow pressure to build in the crankcase. Generally if I have a really dirty engine I will take it to the DIY car wash and use their engine wash and the high pressure spray. Just stay clear of the upper part of the engine with the spraying. And wear some safety glasses. Old plug wires are susceptible to grounding out when wet so it's best to avoid the car wash if your plug wires are old or questionable. Taking some WD40 to spray the plug wires down after cleaning the engine is a good idea. You didn't mention what style of transmission. The front seal on automatics can leak as well as the seal around their dipstick tube adding to the mess. There are dyes you can add to your oil that in combination with a black light can help locate leaks. Some professionals swear by them as they make it easier to find the leak when clean oil is leaking. Good luck on your search.
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. ![]() RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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#4 | ||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Small Block Chevy's just leak... it's what they do. Especially if it's the original engine with high miles and all original gaskets. A lot of them leaked in spots very shortly after leaving the show room floor.
A lot of leaks at the rear of the engine are caused by leaking valve cover gaskets, or the oil pressure sending unit on the back of the block behind the intake manifold. Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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#5 |
Registered User
Join Date: Jul 2007
Location: Toppenish, WA
Posts: 15,509
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Best idea is to grab a can of WD-40, a roll of paper towels and a flat blade #2 screwdriver and your favorite engine degreaser and a pocket full of quarters and head to the quarter car wash and clean the engine and engine compartment as well as you can. WD-40 and towels and screwdriver are to dry the inside of the distributor cap out if it gets condensation in it. get it good and clean and start checking closely .
I've got a 68 292 that ran great but was given to me because in a 180 mile road trip it leaked more oil than it used gas dollar wise. The guy bought the truck drove it home and pulled it in the garage and did an engine swap. That one is going in my 48.
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Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around. |
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#6 | |
Who Changed This?
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Location: Simi Valley, CA
Posts: 10,426
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Quote:
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#7 | |
Registered User
Join Date: Jul 2007
Location: Toppenish, WA
Posts: 15,509
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Quote:
This was after they pressure washed the engine and engine compartment before pulling it. ![]() It's getting painted 48 Chevy truck engine gray with a serious amount of finned cast aluminum on it.
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Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around. |
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#8 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,426
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Brutal! "Take a Saws-All to that exhaust pipe! I want that engine out of here, now!"
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#9 |
Registered User
Join Date: Aug 2010
Location: central oregon
Posts: 155
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Quarter car wash??? my local one is 4 bucks. lol
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#10 |
Senior Member
![]() Join Date: Dec 2009
Location: TN.
Posts: 8,119
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
For sure.
![]() 48 Chev did say a Pocket full So He Knows.
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________________________________________________________________________________________ ____________________________________________ 84 Chevy K-20 63 Impala (my high school car) http://67-72chevytrucks.com/vboard/s...Crew Cab Build |
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#11 |
Registered User
Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 33
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Thanks, appreciate your help. Going to use this, as I work on fixing this issue.
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#12 |
Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,493
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
I really like the Dawn Powerwash for degreasing . Didn’t think it work all that well but I was impressed. If you really want it clean use a heated pressure washer. I rented one and it was well worth it never even took it off the trailer hose was 20 ft long . Like others have said it’s most likely the intake /valve cover or oil line .
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Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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#13 | |
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Join Date: Oct 2009
Location: Denton, Texas
Posts: 1,714
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Quote:
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1968 C10 327, 3 speed manual, LWB stock height daily driver. 1968 C20 327, 4 speed manual, LWB stock height custom camper with heavy duty leaf springs rear, 50th anniversary edition. Hoping to press into daily drive status soon. |
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#14 |
Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,493
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
The motor I took out and replaced ran well but was leaking a lot . Guess the prior owner tried to seal it up . Big ol gob of RTV on the valley of the intake front and back and it still was leaking . I’m going to reseal it and put it in the Anniversary truck
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Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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#15 |
Registered User
Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 33
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Hi, regarding the how many miles question the odometer has 40426, then it has an 8 with a white background. Not sure how many miles would this be?
Below is a picture I took today, not sure if this might be where it is leaking oil. I had the starter replaced recently, and it was covered with oil. Should some hose or some kind of cap go in the valve cover opening (circled in red)? Also, there seems to be a decent amount of oil in bolt (circled in red). Appreciate your advice, on where this oil might be leaking from? |
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#16 |
Registered User
Join Date: May 2013
Location: Post Falls, ID
Posts: 889
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Best engine degrease I have ever found is Totally Awsome from the Dollar store.
I'm dead serious, this stuff will amaze you!! With a cold engine mist everything with cold water. While it's still wet start spraying Totally Awesome everwhere. Let it set for about 5 minutes then spray it off with cold water and watch the grease and grime melt away. Depending in how nasty the engine is, you may need to hit it several times, but it WILL come clean. https://www.familydollar.com/las-tot...20oz/FD1412251
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#17 |
Senior Member
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Location: Studio City, Calif.
Posts: 2,873
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Looking at your picture, are you running it with that hose missing? There is supposed to be a metal connector that plugs into that hole and a tube that runs to the air cleaner. There is another hole on the other side nearer to the front that has a PCV valve and a vacuum hose to the base under the carb. If you are running it with this missing, you will have oil possibly coming out the hole (s) or in other places too. Get those two hoses and the little PCV valve ($10) hooked up and check again.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#18 | |
Registered User
Join Date: Jul 2018
Location: Catskill Mountains,NY
Posts: 8,493
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Quote:
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Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary. |
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#19 |
Registered User
Join Date: Jul 2008
Location: Eastern Oregon
Posts: 2,337
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Get yourself a repair manual for your year pickup. It will show you all the items on your engine and their intended purpose. You mention oil leaking but how does the engine run ?
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71 C-20 07 Magnum RT AWD |
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#20 |
Senior Member
![]() Join Date: Jun 2022
Location: San Ramon,CA
Posts: 504
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
I really like this kind of plastic scraper. They don't tear up the paint or leave a ton of scratches behind, the handle delays my hand cramping up into a claw, and you can sharpen or reshape them on the garage floor in a minute.
You can get these in sets anywhere, this is just an example: https://www.oreillyauto.com/detail/c...aper/pwt0/qss1
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1970 C10 Custom longbed 350/350 |
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#21 | |
Senior Member
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Location: Studio City, Calif.
Posts: 2,873
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Quote:
This is step #1, get those sorted. THEN if it still leaks, look at the valve cover gasket, oil pressure line connection, etc. From the looks of it, he's running around with engine blow-by shooting oil out the open breather like Ol' Faithful.-BA
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#22 |
Registered User
Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 33
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Here are additional pictures. I have had the truck for awhile, but don't drive it too often and I assuming that missing hose/cap has been there all this time (see "Revision" below). The truck has ran well, but right now it's not running too good. I have been driving it around a few blocks every week for about 2 months. When I press on the gas pedal, at 10-20 mph I noticed the truck does not respond well, feels like it needs more gas, not getting the power. I am assuming this opening in the valve cover gasket does not have to do with this, since that opening has been there all this time? "Revision" - actually I had a new carburetor installed about 2 years ago, not sure if the hose that is supposed to go their might have not been installed, but I don't know, maybe it has been without the hose/cap since I got the truck. A two barrel carburetor was replaced with a four barrel carburetor. Might provide a separate thread with more detail about the truck not seeming to be getting enough gas/power and the work that has been done.
Based on the additional pictures, might this help to figure out if what is currently there correct and what I need to put in that valve cover opening? Appreciate your help. Last edited by ggalv; 08-23-2024 at 02:30 AM. |
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#23 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
The way that is set up, all you need to do is plug that hole. You might want to replace the grommet on the PCV (front driver's side) because it looks cracked. FYI, you've got two right side covers. this is what you should have;
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. Last edited by WorkinLonghorn; 08-23-2024 at 09:27 AM. |
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#24 |
Registered User
Join Date: Jun 2019
Location: Chehalis, WA
Posts: 17
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Engines don't have to leak
![]() Don't drive yourself nuts. Clean the engine then use a UV dye kit from your local parts shop. Tells you *exactly* where it's leaking in a pretty short time. But yeah...gotta put a plug in where that open grommet is. May not be your leak, but definitely is chuffing out oil spray. Your local parts place will have a plug, or Summit. |
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#25 |
Post Whore
![]() Join Date: Feb 2016
Location: Portland Oregon
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Re: 1970 Chevrolet C20 Pickup - Motor Leaking Oil
Here is a primer on the crankcase ventilation system. If the system has leaks from bad seals and/or a defective PVC valve it can cause several problems including old leaks. The system is pretty simple and the cost to repair it is low.
https://www.mechanicaleducation.com/...ion-pcv-valve/ Basically low pressure is created in one valve cover so air flows from the breather on the other valve cover into the intake manifold through the PVC valve.
__________________
Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. ![]() RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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