Help with diagnosis: Oil coming up out of the dipstick tube.

[rbwamsley]

I recently picked up ’74 bronco, and I’m having issues diagnosing an issue. I have oil coming up out of the dipstick tub. Based on the knowledge of the previous owner, the engine was rebuilt a few years ago (everything looks stock to me, but this is my first bronco). When I first searched the issue online I came to the conclusion that it was the PCV valve and was an easy fix. I’ve tried the following to remedy the issue.

• Cleaned the PCV valve and made sure the valve could freely move.
• Changed the PCV valve (It was a smaller than the original, but it’s the only one I had laying around the house)
• Changed the oil (thought the previous guy may have put too much in it, and the dipstick could have been aftermarket). This made the issue much worse but only because now there was 6qts of oil, where I had only drained 3qts.

The PCV setup looks correct to me. Here’s a pic.

My next step is to do a compression test on each cylinder and check the plugs for oil.

Other symptoms that may/may not be related:

• There was some oil on the air cleaner plate. It looked old and was lighter in color.
• The engine seems to idle high and drop down to a “normal” rpm when put in gear. I’m not sure if this is an issue or not, as this is my first automatic carbureted car. I’ve read that this could be vacuum leak. If I remove the vacuum line from the carb. the idle drops down to a “normal” rpm.

I would appreciate any help or suggestions you guys could give me.

Thanks,
Blake

 

[Ourobos]

Normally a sign of crankcase pressure. If I'm not mistaken that driver side valve cover should be setup for an inlet, and not have a line running to the breather / intake. The passenger side with the valve should have the line. One side is fresh air in, other side dirty air out to breather basically. Make sure your vacuum on the distributor (advance) and carburetor are hooked to the proper ports on the intake. I too would do a compression test.

 

[bmc69]

Having the inlet air from the "clean" side of the air filter housing is typical and how the factory setup was on most engines. I much prefer that setup to a dedicated breather on the VC in dirty/dusty environments.

That is why many/most of the aftermarket air cleaner assemblies come with the hose connection elbow and a "punch out" in the lower cleaner plate.

You are sure that the PCV valve hose is connected to manifold vacuum source, right?

If all else checks out, a serious blowby condition seems the only conclusion.....

 

[rbwamsley]

Normally a sign of crankcase pressure. If I'm not mistaken that driver side valve cover should be setup for an inlet, and not have a line running to the breather / intake. The passenger side with the valve should have the line. One side is fresh air in, other side dirty air out to breather basically. Make sure your vacuum on the distributor (advance) and carburetor are hooked to the proper ports on the intake. I too would do a compression test.

Thanks for your reply. I'm getting a little mixed up. The current setup is:
Drvr side - Air filter drop plate to oil filler cap via rubber hose.
Pass side - PCV valve into carb. via rubber hose (Not positive about this)

Is there a diagram that show the proper ports the vacuum lines should be hooked up to on the intake and carb?

Thanks,
Blake

 

[rbwamsley]

Having the inlet air from the "clean" side of the air filter housing is typical and how the factory setup was on most engines. I much prefer that setup to a dedicated breather on the VC in dirty/dusty environments.

That is why many/most of the aftermarket air cleaner assemblies come with the hose connection elbow and a "punch out" in the lower cleaner plate.

You are sure that the PCV valve hose is connected to manifold vacuum source, right?

If all else checks out, a serious blowby condition seems the only conclusion.....

It looks to be connected to the carb. Here's a better pic of the PCV valve connection. I'm at work right now, so I can't go look at in the car.

 

[bmc69]

Your setup looks exactly right...factory setup. See link below. Except for one thing ...I still cannot see from your picture that the PCV line is indeed connected to a large (3/8") manifold vacuum port under the carb or in the carb base plate. Something looks funny with your pic....


http://www.autozone.com/autozone/repairguides/Ford-Mustang-Capri-1979-1988-Repair-Guide/EMISSION-CONTROLS/Positive-Crankcase-Ventilation-System/_/P-0900c1528004def8

 

[dave67fd]

Best connection for the PCV valve I think should be the large port at the back/btm of the holley.

The only time I had oil blowing out the dip stick tube is when I replaced the oil pump to a high volume unit. If your motor was rebuilt, maybe that has something to do with it. You may want to make a rubber seal for the stick to seal better.

Confirm your choke is adjusted/working properly regarding the Idle kickdown.

 

[rbwamsley]

Best connection for the PCV valve I think should be the large port at the back/btm of the holley.

Going to have to check on this tonight.

The only time I had oil blowing out the dip stick tube is when I replaced the oil pump to a high volume unit. If your motor was rebuilt, maybe that has something to do with it. You may want to make a rubber seal for the stick to seal better.

Glad to hear this. Any other possible issue besides a bad piston ring makes me happy.

Confirm your choke is adjusted/working properly regarding the Idle kickdown.

Can you recommend a way to do this?

Thanks,
Blake

 

[KyleQ]

Mine did this due to blow-by - it would push oil out of the dipstick bad enough that I pulled the stick out, put a hose on to it into a jug. I would check it once in awhile and and just lift it to pour it back down the dipstick tube.

What does the oil look like out of the tube?

Sorry - but looking at your PCV routing, I'd say someone installed the rings wrong in that motor.

 

[bmc69]

You could cut down dramatically on all of the questions raised so far by simply removing the air cleaner entirely and taking another pic of the pass side of the carb....LOL.

 

[rbwamsley]

You could cut down dramatically on all of the questions raised so far by simply removing the air cleaner entirely and taking another pic of the pass side of the carb....LOL.

Yep. I will be doing this tonight. ;D

 

[rbwamsley]

I think I found the issue. Had my Dad go take pics.

So where is the PCV valve hose supposed to be routed to?

Thanks,
Blake

 

[bmc69]

I think I found the issue. Had my Dad go take pics.

So where is the PCV valve hose supposed to be routed to?


Thanks,
Blake

ha ha ha haaa!..and I thought I'd seen everything. Nope. %)

OK..you see where your power brake booster is attached to the back of the carb?..that is the 3/8" vacuum nipple I referred to earlier, where your PCV hose supposed to be attached. The brake booster, on the other hand, is usually connected to a nipple off of an intake runner at the rear of the intake, something you cannot do with the PCV line. (why?..because the PCV flows air..the vacuum booster requires almost no flow..just the vacuum).

You can "T" the two lines together on that carb port, you might see some minor loss of braking power if you do. I'd give that a try first...because its the easy fix. And you should notice a huge decrease in your blowby problems.;D

I'm pretty sure I see a metal plug in the #4 intake runner, peeking out from under the heater control valve, that is where the vacuum nipple should be for your power brake booster.

 

[rbwamsley]

ha ha ha haaa!..and I thought I'd seen everything. Nope. %)

OK..you see where your power brake booster is attached to the back of the carb?..that is the 3/8" vacuum nipple I referred to earlier, where your PCV hose supposed to be attached. The brake booster, on the other hand, is usually connected to a nipple off of an intake runner at the rear of the intake, something you cannot do with the PCV line. (why?..because the PCV flows air..the vacuum booster requires almost no flow..just the vacuum).

You can "T" the two lines together on that carb port, you might see some minor loss of braking power if you do. I'd give that a try first...because its the easy fix. And you should notice a huge decrease in your blowby problems.;D

I'm pretty sure I see a metal plug in the #4 intake runner, peeking out from under the heater control valve, that is where the vacuum nipple should be for your power brake booster.

Awesome! Thanks for the help. I'll get all this fixed up tonight and report back. I really hope this is causing my issue.

 

[Slednut10]

I think I found the issue. Had my Dad go take pics.

So where is the PCV valve hose supposed to be routed to?

Thanks,
Blake

That's a classic! Good one for the "What the hell were they thinking?" archives!
BMC69 definitely has you going in the right direction.

 

[bmc69]

Hmmm. While we're at it..I see some other potential "funny business" going on with vacuum lines on that engine. From what little I can see, there is some odd combination and routing of the distributor advance vacuum to a "T" that has one line branching off and headed to the rear of the engine....somewhere. Seriously doubt if that's ported vacuum going to the distributor..which means your timing control is wacked and you'll get a very pleasant surprise in how well it will run after all that is sorted out.

And of course the choke is not connected either...

But you sure got a clean looking rig and all that stuff is going to be easy to correct.

 

[01Dudley]

Good luck w/vacuum hoses and I hate to say it, but if that doesn't solve the issue I would say pinched piston ring.

 

[bmc69]

Good luck w/vacuum hoses and I hate to say it, but if that doesn't solve the issue I would say pinched piston ring.

I've seen plenty of engines that exhibited a lot of blowby simply because they had no PCV operating. His has no PCV operating...none whatsoever. And to make matters worse, the crankcase vent "arrangement" that he does have right now is much more restrictive than simply having open breathers on each valve cover would have been. So I can easily see why the oil finds its way out of the dipstick tube in that case.

 

[rbwamsley]

Hmmm. While we're at it..I see some other potential "funny business" going on with vacuum lines on that engine. From what little I can see, there is some odd combination and routing of the distributor advance vacuum to a "T" that has one line branching off and headed to the rear of the engine....somewhere. Seriously doubt if that's ported vacuum going to the distributor..which means your timing control is wacked and you'll get a very pleasant surprise in how well it will run after all that is sorted out.

I was looking at that this weekend. That line runs down the back of the motor to the transmission. Is that completely incorrect?

And of course the choke is not connected either...

Wait, my choke isn't connected? I'm guessing its a heat sink choke. Is it the black box between to the two red lines? What do I need to do to get that hooked up? Sorry, not too familiar with carb'ed motors.

 

[Slednut10]

With all the cash they spent on chrome and making it pretty, (very nice looking rig BTW) they should of at least spent $5 bucks to give you a manual choke cable......