What do you guys think? Guides or rings?

[LarsD]

I've been gathering up parts to do an HCI swap on my 91, however the car has always used oil. Doesn't leak, doesn't smoke when it ides. I had a plugged up PCV system until a couple months ago that was forcing oil into the throttle body. I assumed that was the cause of my oil loss, but I checked it again today and after about 500-600 miles the car has used up another quart of oil. So obviously it wasn't the PCV system, I think it is the guides since the car doesn't puff smoke when it idles, if this is the case then NBD cause I have new TFS heads waiting to go on. However, if the short block is questionable in the slightest then I will get a new engine built for it first. What say you SN patrons?

Thanks

 

[NIKwoaC]

Does it smoke on startup? It's my understanding that bad guides will make the car smoke on startup, since the oil slowly seeps down past the valves while the car is sitting with the engine off.

 

[LarsD]

That is what I have also heard, but I don't know if it does or not, I'll have to get the wife to start it for me I guess.

 

[ID89GT]

What do the plugs look like?

 

[LarsD]

Set that was in the car were pretty hosed up. The ones I put in it I haven't checked since I installed them. Car seems to run fine though.

 

[ID89GT]

If they look oil contaminated I would guess guides from the oil dripping onto them. I don't see how worn rings would get oil on the plugs really

 

[LarsD]

If they look oil contaminated I would guess guides from the oil dripping onto them. I don't see how worn rings would get oil on the plugs really

I would think it would burn off before it could get on the plugs if it was the rings, but if it is seeping on through the guides it could soak in while the car is sitting I guess.

 

[CarMichael Angelo]

Depending on how bad the oil consumption is there is a fairly easy way to tell.

#1 Take off the oil fill cap while it is ideling, smoke puffing out of there indicates poor ring seal.
#2 Have a friend follow behind you (cause you can never see oil smoke out of the rear view mirrors). When you stand on the throttle (if the rings are bad) it'll smoke from crankcase pressure pushing the oil past the rings. When you decelerate after that, it'll smoke from the high vacuum state by pulling the oil past the guides/seals.

 

[CarMichael Angelo]

I would think it would burn off before it could get on the plugs if it was the rings, but if it is seeping on through the guides it could soak in while the car is sitting I guess.

It would also smoke at start up. just start it and get out of the car, It'll smoke long enough for you to see it.

 

[LarsD]

Cool, there is some stuff I didn't think of. Got a nice little list of things to try out, hopefully I don't need to build a new short block yet. Thanks!

 

[Notchbck93]

What Mad Mike posted is good shadetree stuff that works.


Nothing beats a cylinder leakdown test for checking the sealing capabilities of an engine.

My first GT was at 20-22 percent on all cylinders, so she pulled a steady vacuum and power balance test, but the cyl leak down exposed why the car was running 3 tenths slower in the 1/4 as opposed to most others.

I've seen just a simple hone and fresh rings bring back 37 crank hp to a 302.

 

[LarsD]

What Mad Mike posted is good shadetree stuff that works.


Nothing beats a cylinder leakdown test for checking the sealing capabilities of an engine.

My first GT was at 20-22 percent on all cylinders, so she pulled a steady vacuum and power balance test, but the cyl leak down exposed why the car was running 3 tenths slower in the 1/4 as opposed to most others.

I've seen just a simple hone and fresh rings bring back 37 crank hp to a 302.

I'm going to have the next couple of days off, and I was planning on doing that also. I'm trying not to be cheap, but if this short block isn't 5x5 then I'm going to have to build a 347, cause I'm not going to put a 306 back in it. I'd like to not have to do that either cause my Cobra needs a Vortech.

 

[Mintsick]

My guess would be the guides/seals as well, a few years back I rebuilt a 4.3L v6 in an s10 pickup and I had similar oil consumption (1 qt every 500-700 miles) but I never saw any smoke. One day I had new exhaust put on it and made a quick video from the rear, once I started it up I saw the blue puff of smoke. Changed the valve seals out and oil consumption problem was gone.

 

[LarsD]

My guess would be the guides/seals as well, a few years back I rebuilt a 4.3L v6 in an s10 pickup and I had similar oil consumption (1 qt every 500-700 miles) but I never saw any smoke. One day I had new exhaust put on it and made a quick video from the rear, once I started it up I saw the blue puff of smoke. Changed the valve seals out and oil consumption problem was gone.

Hopefully you are right, the rings in my truck aren't in great shape and it puffs blue all the time when idling. This car doesn't smoke at all.

 

[LarsD]

Pulled most of the plugs. The passenger side head plugs looked new, the driver's side plugs not so much. #5 looks lean (no surprise there), #6 is already starting to get cruddy looking, when I swapped these plugs in about 3K miles ago, #6 was so messed up, the gap was almost completely closed off with deposits of some sort. I had the wife start it and I saw no smoke at all. I must have something going on with the driver's side head then, cause the threads on the plugs on that side had oil on them, where as the passenger side plugs thread's were dry.

Here is number 6, you kinda can't make it out, but this one already had some buildup around the base of the plug.

 

[Mintsick]

Are the heads stock as in stock valve seals? I'd still say this would be my first attempt at fixing the oil consumption problem due to it not costing much and is relatively easy to do vs. just tearing down the motor ya know?

 

[LarsD]

Are the heads stock as in stock valve seals? I'd still say this would be my first attempt at fixing the oil consumption problem due to it not costing much and is relatively easy to do vs. just tearing down the motor ya know?

As far as I know they are factory original. I don't care so much about fixing these heads as I have a new set of Trick Flows and a GT40 intake ready to go on the car. I wanted to make sure the short block was good though so I didn't bolt new stuff onto a shot block.

 

[NIKwoaC]

I've seen just a simple hone and fresh rings bring back 37 crank hp to a 302.

Damn, that is quite a bit. How many miles were on the block?

 

[LarsD]

So I'm halfway through the compression test, and all the numbers are within 5psi of each other, which is great, but I'm only getting 85-90 psi. I wonder if I should even bother continuing. The engine is hot, throttle open when cranking, and I left all the plugs in (except for the cylinder I'm testing of course). Is it possible that these numbers are even remotely correct? What I mean is, could the car even run decently with compression this low?

 

[Mintsick]

As far as I know they are factory original. I don't care so much about fixing these heads as I have a new set of Trick Flows and a GT40 intake ready to go on the car. I wanted to make sure the short block was good though so I didn't bolt new stuff onto a shot block.

Ahhh sorry I neglected that piece of information.

I have never done it but isn't there a test when checking compression where you get your base psi and then squirt oil into the cylinder to see if the psi increases to determine if the rings are bad?