Valve stem seals info needed and is it worth while in my case?

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
but 5 and 7 are next to each other
A guy can switch those wires on the cap and not notice.
Coincidentally 5 and 7 are next to each other at the intake manifold and there aint much gasket separating them...wasnt much 40 years ago anyway..
Does the EGR even work?
Didja test it with a vacuum pump?
Didja try re-introducing the crankcase gas via the pcv valve? The carburetor needs that vapor mannnn...

xc_hide_links_from_guests_guests_error_hide_media


Remember Smokey Yunick made that fancy manifold?

I think we're barking up the right tree but i'm starting to wonder if you havent made these troubles for yourself , dude.

Was it 5 and 7 or 4 and 7?
:shrug:
Ok most of your questions I've already talked about before, but it is probably in the spark plug fouling thread not this one. So Your questions will be in yellow, my answers will not.

#1. "Does the EGR work." Well yes the valve itself works, the passages in the intake are plugged. Exhaust will pour out of the exhaust port in the manifold with the EGR valve removed and the engine started. However there is no vacuum on the intake side of the EGR. Hence the ports in the manifold are plugged, as in with carbon.

#2. "Did I test it with a vacuum pump." No. When I bought the truck 4 years the EGR had been removed and a block off plate installed, so I purchased new EGR valve see #1 for why the EGR system is not working.

The PO, was a really good guy and took care of the truck in general but as he got older and his health got poor he did somethings that weren't necessarily the best, anyhow for whatever reason the EGR was blocked off and the vac advance disconnected. I'm not going to recount the entire thread here but to paraphrase the ESC system needs a new knock sensor. The old one is frozen in the block. I know what I'm going to do to fix it but not going to unless I can get the plug fouling / miss fixed. So running with the vac advance disconnected keeps it from pinging even thought the EGR and ESC are non-functional at the moment. I understand that's not right, but it's better than pinging the motor to death.

#3. "Didja try re-introducing the crankcase gas via the pcv valve? The carburetor needs that vapor mannnn..." Maybe I wasn't clear earlier it was late and I'd had quite a bit to drink by then, but PCV was only blocked off briefly during testing. The engine is and has always been run with a fully functional PCV system.

#4. Remember Smokey Yunick made that fancy manifold? Ya.

#5. "I think we're barking up the right tree but i'm starting to wonder if you havent made these troubles for yourself , dude." I doubt I've made these troubles. But you might have. Your location seems to be my Mom's house, and you have been there for quite a while, so if your there you probably know where I live came over and messed with my truck. For the record your not the first person to bring up the intake thing, I've just been really hesitant to believe that's the problem since it passes testing.

#6. "Was it 5 and 7 or 4 and 7?" Your talking about 5 & 7
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
Fine.
I want to double down on bad intake gasket - between the 5 and 7.

Take pictures.
Ok, if I pull the intake I'll take pictures of whatever I find just for you. I'm taking this discussion over to the spark plug thread as there is something I'm going to post over there that I want you to see, but I'll just say you might be on to something with the "between 5 & 7". Thread is here: https://www.gmsquarebody.com/threads/spark-plugs-over-thinking.35774/ Thanks.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
3,626
Reaction score
4,897
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
Ha! What I’m about to share has no actual bearing on your engine, but I thought of you yesterday after getting frustrated with my old mower, and pumping about $400 worth of various parts into it….thinking about what is literally my only other good option to fixing it, is driving my happy ass down to Oregon and plopping down $10k+ for a new mower.
Used market for zero turn mowers up here and anywhere in the PNW has always been expensive and few and far between.
Good news is, $400 and a little cussing has the mower (which has low ish hours but was neglected by the prev owner) running like a top again.
But every time I pull maintenance on it or repair something, I find something else that “shouldn’t “ be wrong, but is….lol.
(Most of which is attributable to the PO leaving it outside in the rain…)

Btw if you see a good condition 60” or bigger commercial grade zero turn for sale (not the happy homeowners versions) let me know please!
I’ll keep my eye out for a rebuilt 350 for you!
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
Ha! What I’m about to share has no actual bearing on your engine, but I thought of you yesterday after getting frustrated with my old mower, and pumping about $400 worth of various parts into it….thinking about what is literally my only other good option to fixing it, is driving my happy ass down to Oregon and plopping down $10k+ for a new mower.
Used market for zero turn mowers up here and anywhere in the PNW has always been expensive and few and far between.
Good news is, $400 and a little cussing has the mower (which has low ish hours but was neglected by the prev owner) running like a top again.
But every time I pull maintenance on it or repair something, I find something else that “shouldn’t “ be wrong, but is….lol.
(Most of which is attributable to the PO leaving it outside in the rain…)

Btw if you see a good condition 60” or bigger commercial grade zero turn for sale (not the happy homeowners versions) let me know please!
I’ll keep my eye out for a rebuilt 350 for you!
Thanks, that's the story of my life lol. Go to fix something and find a couple other things that aren't right but still function.

I can't make you any promises but I will keep an eye out. We have a couple landscape companies that come into the shop so I will ask them. Also giving serious consideration to pulling the intake and seeing what's going on there. Two weeks from now I'm going to have a big feed haul for the farm so we will see.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
3,626
Reaction score
4,897
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
Thanks, that's the story of my life lol. Go to fix something and find a couple other things that aren't right but still function.

I can't make you any promises but I will keep an eye out. We have a couple landscape companies that come into the shop so I will ask them. Also giving serious consideration to pulling the intake and seeing what's going on there. Two weeks from now I'm going to have a big feed haul for the farm so we will see.
Yeah, no worries. Appreciate it.
If your truck's not up to snuff by 2 weeks from now, I'll make you a deal. You can use my K20, for freee, I'll even fill both tanks! Slight caveat, I'll need you to re-assemble it in order to use it. Shouldn't take u too long bein a mechanic and all! ....lol
But it'll pull. Had no trouble holding 65mph on Hwy 18 over Tiger Mountain with a 6klb boat behind it!
 
Last edited:

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
Yeah, no worries. Appreciate it.
If your truck's not up to snuff by 2 weeks from now, I'll make you a deal. You can use my K20, for freee, I'll even fill both tanks! Slight caveat, I'll need you to re-assemble it in order to use it. Shouldn't take u too long bein a mechanic and all! ....lol
But it'll pull. Had no trouble holding 65mph on Hwy 18 over Tiger Mountain with a 6klb boat behind it!
Ya that's some kind of deal your offering! Sometime we should probably meet, being as we live so close and all.

I have no doubt my truck would make the trip even as is. I'd just take an extra plug and my AAA card, actually I know longer have AAA.

Side topic if your game. I was a long time AAA member, mainly because of the towing, I know I can fix a lot of stuff on the side of the road, but for me I just felt more comfortable having it. I had a couple bad experiences you know worse than usual. And eventually switched to a company called better world, because they will tow my truck and trailer 100 miles, or RV 100 miles. And it covers medium duty vehicles as well. What do you know but in the 5 years I've been a member I've not used their service which is just fine with me!

As you'd expect my 305 is no power house, but overall it's been a good motor and has done what I've asked it to. Trailers over Tiger mountain is wide open 50 - 55 mph affair, but I look at it like this, at least I get to pass the semi-trucks!
 

Rusty Nail

Victim of Culture
Joined
Jan 29, 2015
Posts
8,592
Reaction score
7,261
Location
Your mom's house
First Name
Rusty
Truck Year
1977,1988
Truck Model
C20, K5
Engine Size
350, 350
Say ol boy, just cuz I'm curious, what color of antifreeze is in that engine AND did it ever have a different color in it?

Figure out how you flipped the ring yet? Plugging up that PCV hose with your cloggy intake maybe?
Is there MMO in the crankcase yet?
What about in the gas tank?
Hmm?

Did ya try burning any trans fluid yet?
We'll get it flipped back over dude don't fret.
Prolly ought change the oil.
 
Last edited:

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
2,141
Reaction score
2,891
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350

You've gone down a rabbit hole. It's not rocket science.
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
Say ol boy, just cuz I'm curious, what color of antifreeze is in that engine AND did it ever have a different color in it?

Figure out how you flipped the ring yet? Plugging up that PCV hose with your cloggy intake maybe?
Is there MMO in the crankcase yet?
What about in the gas tank?
Hmm?

Did ya try burning any trans fluid yet?
We'll get it flipped back over dude don't fret.
Prolly ought change the oil.

Thank you for bringing up the intake manifold gasket again and reminding me that is possible cause. I hope have you have a nice day.
 
Last edited:

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350

You've gone down a rabbit hole. It's not rocket science.
Your absolutely right. Thanks for the link. I see you went in a similar direction thinking it was stem seals initially. I'm sorry but I can't think of time that I saw one of these intake gaskets leak anything other than coolant or external vacuum leak, so that made me hesitant to believe it could be the intake sucking oil, but now I can see it's happened to a few folks on here.
 
Last edited:

greyghost

Junior Member
Joined
Jun 15, 2022
Posts
22
Reaction score
4
Location
kansas
First Name
vic
Truck Year
1981
Truck Model
C10
Engine Size
250
air pressure test first to see valves are seating properly, a leak down test all cyl. before changing both seals, and check valve side play at full open n 50% open, to slopy n seals wont help, be prepared to get new cat. longterm oil exposure with plug up cat in few months
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
3,675
Reaction score
3,910
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
air pressure test first to see valves are seating properly, a leak down test all cyl. before changing both seals, and check valve side play at full open n 50% open, to slopy n seals wont help, be prepared to get new cat. longterm oil exposure with plug up cat in few months
Ok, So to summarize for anyone that comes along and sees this thread but doesn't really read it all. Before doing the stem seals I did a compression test all the way around and leak down on the offending cylinder #7. Passed all testing. I did the seals with the heads on the truck so play was not checked, it was just a quick wham bam thank you ma'am, and I only did #7. In my case the stem seals were NOT the issue. Linked above in post #57 is the spark plug thread where my oil control issues is discussed and solved by replacing the intake gasket as it was sucking oil out of the valley.

As for the Cat it survived just fine.
 

greyghost

Junior Member
Joined
Jun 15, 2022
Posts
22
Reaction score
4
Location
kansas
First Name
vic
Truck Year
1981
Truck Model
C10
Engine Size
250
good job, side play in valves tough fix without pulling heads, tube shims i dont mess with, knurl stems, shim guides, new valves,much more than that, pick heads you really want 1.98 In 76cc or less chambers ,port yourself. 50 to 75 ponies w/right cam....thats a rarity leak from intake,any idea what caused it... curious why change heads on crate engine? chevy crates are well match performance engines, shortblock way cheaper build than crate, LS or Gen I 350 even better, but thats my favs
 
Last edited:

Latest posts

Forum statistics

Threads
36,492
Posts
773,039
Members
25,858
Latest member
2manyburbans
Top