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Old 02-27-2015, 06:10 AM   #101
gmcnoob
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Re: 86 GMC Sierra Classic 2500 questions

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My suggestion would be to wipe the oil off and run the engine with the hood up.
Try and see if you can see where the oil is coming from. If the valve covers were leaking there would very likely be smoke coming off the exhaust manifolds.
I'm suspecting that breather up top, but I'm not seeing oil on top of the valve cover so thats probably not it.
I will take your advice on that heater hose. So just to be clear if it appears that there is oil coming out of those intake manifold bolts am I going to have to completely remove the intake manifold and redo the gaskets? Or could it be as simple as pulling the leaky bolts out and putting some kind of thread sealant on there and tightening them down again? This leak has been more frustrating than my electrical gremlins were. I'm fairly certain that the mechanic did a good job sealing up those valve covers but there's still some oil from when it was previously leaking that is still burning off so I am currently getting a little bit of smoke. Also can you tell me what a normal oil pressure reading would be? After the guy fixed the valve cover problem it's running between 50 and 60 which is much higher than it was when the valve cover was gushing oil. Of course it lowers to about 30 or so when I'm stopped.

Thanks for your advice by the way. I'm learning a lot from you guys.
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Old 02-27-2015, 06:16 AM   #102
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Re: 86 GMC Sierra Classic 2500 questions

One more thing I wanted to mention was he told me to start using 15w40 instead of 10w30. I didn't really understand his explanation as to why I should do that.

I also read another thread that said to check my oil pressure sender and line... I had never considered that before. Is that a possibility?

Last edited by gmcnoob; 02-27-2015 at 06:22 AM. Reason: Additional question
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Old 02-27-2015, 07:29 AM   #103
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Re: 86 GMC Sierra Classic 2500 questions

At this point I would be checking anything and everything.
Supposedly running a thicker weight of oil will slow leaks and reduce lifter noise, Im not sure if I would go so far as to run 15w40, but I have run 10w40 no problems to reduce what I thought was lifter tap.

My truck always runs 60 when cold, once it warms up it dips to 30 or lower which is normal. You should see it vary wildly with throttle position.

Now my mechanic told me the 350 has an internal oil pump, so if it was leaking or otherwise not functioning properly, that I would have zero pressure or it would simply leak into the oil pan.
I'm not sure if that is totally correct, but he had been doing Chevy trucks forever so I'm inclined to believe him. That being said I think the pump is driven by the distributer, so I'd check there.
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Old 02-27-2015, 11:31 PM   #104
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Re: 86 GMC Sierra Classic 2500 questions

Your oil pump is fine. Those pressure readings seem normal to me. As for the oil leak you could start by just pulling one intake bolt at a time and apply some aviation gasket sealer to the threads than re-install. I have had coolant puddle up on the intake before from the manifold bolts leaking, but never oil although it could be possible. I would start by applying sealant to the intake bolts first though as thats cheap and easy to do. Good luck!!!!!
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Old 02-28-2015, 06:54 AM   #105
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Re: 86 GMC Sierra Classic 2500 questions

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Your oil pump is fine. Those pressure readings seem normal to me. As for the oil leak you could start by just pulling one intake bolt at a time and apply some aviation gasket sealer to the threads than re-install. I have had coolant puddle up on the intake before from the manifold bolts leaking, but never oil although it could be possible. I would start by applying sealant to the intake bolts first though as thats cheap and easy to do. Good luck!!!!!
Thanks. This will be the first thing I try today.

Just when I think everything is almost done I run into more stuff to wrench on. I was messing around yesterday checking and cleaning all of my brakes. Rear drums and shoes are in good shape. I couldn't believe how massive and heavy that drum was compared to my car. Front rotors and pads also good except for one thing. I broke the passenger side bleeder valve way back when I started messing with the truck and realized that side never got bled. Broken bolts have become my worst enemy. Because I'm an idiot I always wondered why the truck pulls to the left a little while braking.... It's because I never completed the job. Long story short, that bleeder is not coming out. I wasted more time than I care to admit trying to get it out. The question is can I get away with replacing the one caliper and reusing the current pads or is it new calipers and pads for both sides? I think it know the answer but am looking for confirmation.

A couple of things I would recommend to any beginner like me. Always use some type of anti seize for certain bolts and always use dielectric grease for your bulbs and other electrical connections. Some of the experts here can correct me if I'm wrong on that but I think it will save you the frustration I have gone through.... And whatever you do, don't break bolts. Just don't. Be patient and don't try to force them like I did.
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Old 03-04-2015, 08:24 PM   #106
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Re: 86 GMC Sierra Classic 2500 questions

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Thanks. This will be the first thing I try today.

Just when I think everything is almost done I run into more stuff to wrench on. I was messing around yesterday checking and cleaning all of my brakes. Rear drums and shoes are in good shape. I couldn't believe how massive and heavy that drum was compared to my car. Front rotors and pads also good except for one thing. I broke the passenger side bleeder valve way back when I started messing with the truck and realized that side never got bled. Broken bolts have become my worst enemy. Because I'm an idiot I always wondered why the truck pulls to the left a little while braking.... It's because I never completed the job. Long story short, that bleeder is not coming out. I wasted more time than I care to admit trying to get it out. The question is can I get away with replacing the one caliper and reusing the current pads or is it new calipers and pads for both sides? I think it know the answer but am looking for confirmation.

A couple of things I would recommend to any beginner like me. Always use some type of anti seize for certain bolts and always use dielectric grease for your bulbs and other electrical connections. Some of the experts here can correct me if I'm wrong on that but I think it will save you the frustration I have gone through.... And whatever you do, don't break bolts. Just don't. Be patient and don't try to force them like I did.
I hear you on the broken bolts. I use to break bolts all the time when I was younger than I realized that I don't need a 3/8" ratchet for a 1/4" bolt. Lol
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Old 03-04-2015, 11:43 PM   #107
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Re: 86 GMC Sierra Classic 2500 questions

Oil on intake: yes, just remove the bolts one at a time, clean them, apply some sealer, then reinstall. The bolts pass through the head and are exposed in the valley, where the oil flies around when the engine runs.

Replacing one caliper: you are fine replacing the caliper and reusing the pads. Are you sure you can't use Vise-Grip or similar pliers to remove the bleeder screw? Make sure to soak it a couple of times a day, for a few days with something like PB Blaster or Liquid Wrench before attempting to remove the bleeder. Another option would be to use a 6-point socket slightly smaller than the original size, tap the socket on with a hammer, and use a long lever to remove the bleeder.
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Old 03-05-2015, 08:10 AM   #108
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Re: 86 GMC Sierra Classic 2500 questions

I can never take out broken bleeders and they aren't worth spending a lot of time on them. I can snap them off with 2 fingers when they are rusted in. I just buy new calipers

I will never get talked into anti-seize. I don't even allow that messy s**t in my garage. It gets on anything and everything if you aren't careful, and I ain't careful enough apparently. Best of luck to anybody else that likes it.
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Old 06-19-2015, 03:38 PM   #109
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Re: 86 GMC Sierra Classic 2500 questions

I am about to buy new calipers and the site I'm trying to buy them from says the code will be on my service parts identification sticker, JD6 or something like that. I do not see that on mine. How do I know if I'm purchasing the correct ones?
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Old 08-25-2015, 12:14 PM   #110
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Re: 86 GMC Sierra Classic 2500 questions

For awhile everything had been going well with this truck thanks to the help I have received here but now I'm back.

It is now pulling oil into the air cleaner housing from the breather. A decent amount of it too. PCV is working fine.

The engine is old and I'm sure there is plenty of blow by but it seems excessive to be pulling oil into the air cleaner. I know a rebuild is probably the answer but are there any other suggestions?

I don't want to keep pulling oil into the air cleaner but I see no other option.

This might be a dumb question but can a different exhaust cause any of this? The old muffler was rusty and full of holes so I just slapped some cheap thrushers on there. Don't know if that could be causing issues.
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