Bad valve guides?

Messages
1,815
Location
South Dakota
I replaced the valve stem seals ony 1991 Chevrolet K1500; 4.3 V6. The mechanic stated that the valve guides are bad. I am no mechanic and don't know all of the ins and outs of engine mechanics. The engine seems to be smoking as bad as before or worse.

What should I expect if I replaced the valve stem seals but the valve guides are bad? For the record, I've been driving it this way for 6 years. I thought that stem seals would be a cheap and easy fix. I expect that the engine will outlast the truck body. I probably won't sink any additional money into it.
 

Astro14

$100 Site Donor
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13,103
Location
Virginia Beach
Valve guides hold the stem of the valve and allow it to move up and down. If they’re worn out, the valve moves laterally in operation and lots of oil can get past.

New seals won’t last long on top of worn guides. Seals are an easy job. Guides require pulling the heads.

I’d keep the oil topped off and drive it.
 
Messages
2,867
Location
pa
i believe if the seals are like the older V-8 they are a poor design O ring type, better ones are available but if the guides are loose they need reworking + having a machine shop install bronze guides + modern seals + a "valve job" while heads are off if you intend to keep your ride. knurling is a cheaper but short lived option. otherwise how is the engine + how many miles??
 
Messages
246
Location
South
Im sure some may argue this recommendation but after a lifetime in the fleet management world here’s mine...
Install both umbrella and factory style o-ring valve stem seals. Even if there is guide wear both seals will slow the oil consumption considerably. Our fleet had 200+ Chevy 1500 pickups and Blazers all with the 4.3.
 
Messages
1,881
Is this truck a TBI engine? If so, every Chevy TBI I’ve owned (I’ve had close to 10) has puffed blue smoke on startup. Most of them I’ve never kept long enough to fix, but one of them I did. I had the valve seals replaced which stopped the oil puff on startup. A few years later it started happening again and was diagnosed as valve guide wear which would require a valve job.

I never got around to repairing it.
 
Messages
1,790
Location
RI
The OP already replaced them and he said it’s just as bad if not worse.

You’ve got 3 choices.

Pull the heads and fix them

Sell the truck

Live with it
 
Messages
2,148
Location
missouri
if you pull the heads odds are you will end up with oil consumption because the friction lock between the bores and the head will be broken and the torque when put back on will be different, resulting in out of round bores.

If you use the same exact head gasket, and clean threads, and torque carefully you might get by. But factory torques all of them at the same time, you can not duplicate that.

Put on the umbrella seal and it will be fine.

Rod
 
Messages
25,951
Location
MA, Mittelfranken.de
if you pull the heads odds are you will end up with oil consumption because the friction lock between the bores and the head will be broken and the torque when put back on will be different, resulting in out of round bores.

If you use the same exact head gasket, and clean threads, and torque carefully you might get by. But factory torques all of them at the same time, you can not duplicate that.

Put on the umbrella seal and it will be fine.

Rod
Where pray tell did you find this gem of misinformation?
 
Messages
1,790
Location
RI
if you pull the heads odds are you will end up with oil consumption because the friction lock between the bores and the head will be broken and the torque when put back on will be different, resulting in out of round bores.

If you use the same exact head gasket, and clean threads, and torque carefully you might get by. But factory torques all of them at the same time, you can not duplicate that.

Put on the umbrella seal and it will be fine.

Rod

That’s some story you’ve got there.
 
Messages
2,148
Location
missouri
Worked for a used car dealer in the 80's during a layoff. GM small block small block were infamous for burning oil after a valve job. It was common before aluminum heads.
The owner used good old farm dust in the intake to lrt them reseal. Does not take much. It does work long enough to get him the money for the truck. I hated that job. They also make smokeless oil. It does work for smoke. He also did roll backs, I never did any of those things, just valve jobs. He was Indian, moved to the reservation to avoid jail. Quapaw Oklahoma GM 4.3 V6 has cast heads.
 
Messages
246
Location
South
The OP already replaced them and he said it’s just as bad if not worse.

You’ve got 3 choices.

Pull the heads and fix them

Sell the truck

Live with it
if umbrella seals ONLY were used it won’t stop smoking and using oil. you need both umbrellas and o- ring seals.
 
Messages
246
Location
South
Only did umbrella seals.
It’s worth a try to pull the valve covers and install the O-rings. Dont even have to disturb the umbrellas. Compress the spring with retainer/rotator below the spring retainer and keeper grooves and slide the O-ring on the stem. Position the keepers in the grove just above the O-ring and slowly release the retainer and spring. This seals the stem and retainer where most of the oil will be diverted. The umbrellas shield any oil pooling around the guide during normal drainback. It works. I’ve seen it on 100s of 4.3 V6s, and V8s - 262s, 267s, 305s, 350s, and 400s. Had all those in our 1,100 vehicle fleet since 1981.
 
Last edited:
Messages
23,894
Location
CA
if you pull the heads odds are you will end up with oil consumption because the friction lock between the bores and the head will be broken and the torque when put back on will be different, resulting in out of round bores.

If you use the same exact head gasket, and clean threads, and torque carefully you might get by. But factory torques all of them at the same time, you can not duplicate that.

Put on the umbrella seal and it will be fine.

Rod
I have a feeling that someone came up with this answer in an effort to explain a situation, but the answer is incorrect.
 
Messages
1,881
I’m glad to see there’s so many “mechanics” here. Let’s all “assume” it’s the valve guides/stem seals 😂
I take it you don’t have much knowledge about engines.

The late 80’s- early 90’s GM TBI engines are notorious for valve seal degradation and valve guide wear. Known fact.
 

BlueOvalFitter

Site Donor 2021
Messages
9,509
Location
Cajun Country, La.
i believe if the seals are like the older V-8 they are a poor design O ring type, better ones are available but if the guides are loose they need reworking + having a machine shop install bronze guides + modern seals + a "valve job" while heads are off if you intend to keep your ride. knurling is a cheaper but short lived option. otherwise how is the engine + how many miles??
If I'm not mistaken the valve seals are the umbrella type. That's a cheap easy fix. But as Astro and benjy stated, if the guides are wore then seals won't help.
Good luck.
 
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