Topic: Bent push rod and oil on the plug?

[65springtime]

I put new plugs in the Mustang and drove a few miles and noticed a little knock so I pulled the valve covers and found one of the rocker arms was not on the push rod so I also pulled the intake manifold (was going to pull it anyway) and sure enought the push rod was bent. I pulled all the plugs out and the plug on number 3 pistion had oil on it and that is where the bent push rod was. What would have caused oil to be on the number three plug? Thanks

[jethat]

A damaged piston ring or a damage piston.. if you have another push rod you could put it in and do a compression test but most likely you got some piston damage and it will bend the pushrod again.. might be time for a overhaul or get another engine..

[65springtime]

This is the OE 289 engine that came on the car and will not be getting another engine. If it is the piston then an overhaul is in order. I have a new set of push rods.

[Jeff73Mach1]

Pushrods get bent from overrevving, improper adjustment, detonation, backfire and other things as well.

I wouldn't take a bent pushrod to mean much on its own.  Oil on the plug is usually from blow by and/or bad valve stem seals, but an inoperative PCV system can lead to plug fouling as well.  While it may be true that a broken ring or damaged piston is possible, I wouldn't jump to that conclusion.

BTW not many people realize how often spark plugs are bad.  Dropping a plug can cause it to not function properly without any visible damage to the exterior of the plug.
Just because you didn't drop it doesn't mean it wasn't dropped.

How far did you drive and how much oil was on the plug?  What color was it?  Was it an intake or exhaust that had the bent pushrod?

A compression test will tell part of the story.  A mechanic's scope can look through the spark plug port and see some types of damage.

[65springtime]

I am no mechanic but I would say intake because it is not over the exhaust port. After putting in the new plugs drove it about 20 miles and the car just was not running right still. Had the carb rebuilt and a lot of other things but the knock got to me and I was going to paint the engine and pull the intake anyway and that is when I found the bent rod. We did not drop any plugs. There was not a lot of oil just enought to get it wet. The color looked norman. You can push the valve down easy. Just could not understand the oil on the plug. The guy I bought the car from was only about 19 so yes he could have over reved it because he sold the car because he was scared of the manual shifting. He dould not handel it. So he could have. He did not have the car very long. Also when you let out on the clutch from a stop, you would have to play with the clutch to keep the car from jumping a little just when starting from a stop. Could that be the clutch itself? I really appreciate the help.

[Jeff73Mach1]

Could be the clutch or high idle speed.  I'd put it back together and drive it (easily) a bit and see.  If the engine needs a rebuild, it is unlikely to matter unless you throw a rod and damage the block. if it was an intake, then you might have been fouling due to the intake valve not opening enough to get a proper mixture.

If it fouls again after another 50 miles I'd have a mechanic put a scope in the cylinder and look at the top of the piston and the valves for damage and the cylinder walls for scoring.

The scopes are a few hundred bucks or more IIRC  Compression test is also a good check for bad rings.  Run it with all plugs out and if a cylinder is low add a teaspoon of motor oil and repeat-if compression is higher the 2nd time (with the oil) the rings are generally either stuck, broke, or worn.

Stuck rings will free up sometimes with more frequent use and oil changes, but not always.

[jethat]

Sounds to me like you got a car from a kid who may have damaged the engine and all.. We are talking about a 45 year old engine. Why waste money diagnosing a deal that in the end needs an overhaul and you already know that. Bent push rod oil on the plug knocking sound.. Me I'd yank the motor and tear it down.. Having an old engine rebuilt to stock specifications generally isnt that expensive in the overall scheme of what you can spend on these old cars. Once that's done you know the engines good and you can move on to other stuff with the car.

[65springtime]

Yep, I think that would be the right thing to do. Just about have it tore down as it is.

[Joe AZ 2 PA]

Yep, I think that would be the right thing to do. Just about have it tore down as it is.

John,
Good thing you're retired. One thing for sure you are learning a lot about fixing an older Mustang from the guys in this group. . . . . 

[65springtime]

You are right and believe it or not, I am loving every minit of it. These cars are so easy to work on. I am no mechanic by any means but even I can tear it down and do a lot of the work. But that is also why they have machine shops. I am in no hurry at all. I just play with it now and then. Buying a lot of new parts for the engine and when I get that right I will move on to the front end, steering, shocks etc. Then the front floor plans. Driver and passenger toe boards need replacing. Not big holes but enought to be replaced. The last thing will be new Base coat/ clear coat paint job. The PO installed air shocks on the rear and they have to go for sure. Do not like them and not good on the metal back there.   

[Joe AZ 2 PA]

Good plan. . . . 

[65springtime]

Was told by a mechanic and car racer that with a bent push rod most likely I have a bad valve seal because of the bent push rod. So I will be putting in new hardened seals also. No more adding an aditive to the gas.

[Joe AZ 2 PA]

Good idea. Next time mine is down I plan to do the same. . . . 

[55dsofastback]

John,
Is the rebuild under way? and I know you will look but since the engine will be out nows the time to take a look at that clutch since it was giving you a some problems you had mentioned earlier.
Just a thought
Let us know how it goes.

Chris

[65springtime]

No, have not pulled the engine at this time. I am in no hurry and I have decided to install a new clutch kit when I have it out. Man, it has just been too hot to do anything and do not have air where the car is. I will have the engine gone over and will also be installing new hardened seats. (no more aditives to gas) Will keep you all in touch when I do get the engine pulled. It is really ready. I have everthing out except the engine. Also have in intake off, so just need to unhook the bottom. Not sure if I will pull the trans out the same time or now. I have all new parts, new oil pan, everthing in the engine compartment will be new including the nuts and screws. Windshield washer pump etc. (all new) When I get the engine done I will move to the underside with new shocks, springs exhaust and front end parts that need replaced. Transmission shifts great, just the clutch is bad. Once you get going the clutch works just fine. Someone told me the clutch had chatter. What ever that is. Anyway I will be replacing it with a nice Zoom kit. I enjoy working on these and will just take my time.

[65springtime]

I just noticed I have already said most of this abouve on an earler post. Oh well. I am at the age where it is leagal to do that.

[55dsofastback]

Hey it's new to me, even if you repeated it. My mustang had a 3 speed in it when bought it, never had any chatter. I would vote to pull the tranny 
 at the same time you pull the engine, but hey,  sounds like you got everything under control and like you said there's no rush. It took me and my brother in-law about 5 years to do my fastback. Buy part here and there save up buy another part, I do think it made me appreciate it more. Heck after 18years  of owing this car I still get excited every time I see it not to mention drive it and I'm still doing work on her, there are a ton of things I still want to do. I'll stop rambling, Thanks for update and I look forward to more on how your restoration goes.

Chris

[65springtime]

You said you "had a three speed in the car when you got it" Do you still have the three speed or did you do an upgrade? I would love to have a four speed but need other parts first. Someday maybe. I just love the feel of going through te gears. I have had a lot of four speeds in my life. Ever time I got a 55-56 Chevy the first thing I did was thake out the auto and install a muncy (sp) four speed. But that was when the 55-57 where cheap. Not like today. The last 57 I had was a 57 Chevy NoMad. It was really sharp but sold it back in 84 for only $2,400.00. You know what they are worth today. Had a 65 Mustang Rag top and sold it back in (I think) 83. Man, it would have been nice if I had all them today. So what ever you do, do not sell your Fastback because you will really regret it and I am planning on keeping my coupe.  (unless you wanted to trade me even)  lol 

[55dsofastback]

I did upgrade, to a T-5 transmission. It is a beautuful install. NO modification needed, bolts right in, only thing your changing is the crossmember  and that too just bolts right into the frame as the original did. Going from a 3 to a 5 speed is night and day! LOVE IT.
If you like going through the gears I highly recommend it.  Before Mustangs I would help my brother in-law with his 57 chevy convertible. I remember when he sold it back in 1979 for $12, 500 it was beautiful! and I remember thinking... WOW thats alot of money  we all know what they go for now. MAN I wish you had the Nomad too,  that is my other favorite car to have: 55 or 56 Nomad...oh man! It's nice to dream.  And keep dereaming about that trade too 

[65springtime]

I did upgrade, to a T-5 transmission. It is a beautuful install. NO modification needed, bolts right in, only thing your changing is the crossmember  and that too just bolts right into the frame as the original did. Going from a 3 to a 5 speed is night and day! LOVE IT.

If you do not mind me asking, where did you get your T-5? Yes, I would love to put one in "Someday". My Noman was a '57. Had the power pack 283 engine, all the chrome on the inside was perfect. The whole car was perfect. It was all OE. OE wheel covers. Man, would be nice to still have it.