Author Topic: 351C blows oil out of the valve covers (Read 8673 times)

Jeff73Mach1 · « **on:** August 09, 2009, 09:39:18 PM »

I just bought a 73 Mustang Mach 1 Fastback with a 351C 4v and a 4 speed transmission. It has a Torker intake and a holley carb. I drove it home and had some problems along the way. The car had been a show car and has a great paint job of a straight rust free body and a nice original base interior with a full console, hurst shifter and fold down rear seat.

On the trip home it started off smoking so I stopped, checked the oil and was 2 quarts low. I added 10-40 and headed on my way. I noticed the PCV valve was not in all the way so I fixed that. I stopped again 20 miles later only to find that I was again 2 quarts low and had blown oil out of the valve covers, all over the hood and engine compartment. I pulled the PCV Valve and left it hanging which seemed to help as the car quit spewing oil and blowing blue smoke, and I added 2 quarts of 20w50. It stopped smoking and leaking oil,(well at least not spewing oil).

I thought the PCV valve was bad so I stopped along the way and picked up a new PCV Valve, installed it and the oil geyser returned, this time blowing the dipstick out and again spilling oil like a tanker.

The engine has a rough idle and I thought the timing might be off so when I got home I hooked up a timing light and pulled the vacuum line. The timing seems way off, but the distributor won't turn with the hold down clamp loosened. I've sprayed penetrating oil and am waiting to try again.

With the PCV Valve out the exhaust doesn't look at all smokey and the engine pulls good and hard up to 6000 RPM's but idles roughly

Oil pressure on the stock gauge has stayed high throughout the trip home (125 miles or so) and a short test drive, but stock gauges don't inspire confidence.

Rear end code shows the car should have a 3.5 rear gear, but the 235-60-15 tires and the 4000 rpm at 70 GPS measured suggest the rear axle ratio is more like a 4.56.

I will need to sort out the front suspension and the shifter needs bushings and adjustment. Currently i cannot get the car to go in gear!

So my question is, what is causing my engine to spew oil? There is no water in the oil, and no bubbles in the radiator while the engine is running, so I am not inclined to think it is a blown head gasket (not ruling it out though) and the smoking cleared up the PCV valve pulled and heavier oil, so I am thinking it is either worn rings allowing the crankcase to become pressurized or a cracked cylinder wall

Also the timing issue bothers me as it shouln't run well that far out of time. I suspect a slipped balancer, but how much vibration would that cause at speed. I would have thought a lot, but the engine only seems to vibrate or shake at below 700 rpm.

I pulled and installed a short block 302 in my 1972 Mustang Coupe 20 years ago and I can do it, but 20 years makes the prospect of laying under a car to unbolt stuff far less attractive.

I did search folks, and I'm sorry for being long winded, but I am frustrated at not being able to diagnose this problem.

Jeff73Mach1 · « **Reply #1 on:** August 10, 2009, 11:32:35 AM »

Well I may have isolated the oil problem. The prior owner had aluminum valve covers installed. The oil fill is the non vented type and should be vented. While I need to do a few checks to verify that this is the primary problem, I at least have a working theory that doesn't involve a catastrophic engine failure!

Soaring · « **Reply #2 on:** August 10, 2009, 02:52:53 PM »

Kids put those aftermarket valve covers on just for the looks and don't understand that the engine needs to breathe out the breather cap on all carbureted engines. The PCV system also has to be working.

Jeff73Mach1 · « **Reply #3 on:** August 10, 2009, 02:59:12 PM »

The "Kid" I bought it from was in his early 60's and had a Midas install them. The receipt indicated the original valve covers were beyond their useful life or something like that. LOL

Now on to the shift problems . . . (I know pretty much what they are, I just have a boat engine to reinstall before I get to them-summer is almost over you know.)

Soaring · « **Reply #4 on:** August 10, 2009, 03:40:10 PM »

Then, the "kid" was an idiot. Working on a boat, huh? I owned one of those holes in the water into which you pour money.

If I ever do get another one it will be an inboard that I can work on. Something with a Volvo engine.

Jeff73Mach1 · « **Reply #5 on:** August 10, 2009, 03:43:02 PM »

Marlin Ski Magnum hull up rebuild. Mercruiser 350 Magnum Skier engine Had it out a few times and lost the main bearings after the rebuild and am dropping the now rebuilt again engine in tonight (if I feel like it)

Never would I work on and IO, though outboards aren't terrible

Soaring · « **Reply #6 on:** August 10, 2009, 03:47:16 PM »

I had a 150 Johnson outboard, and it was always giving me fits with the computer, etc. The boat was an 18' walk-through and I really liked it as a ski boat because you could carry a lot of people, but the engine was crap. And, since I knew nothing about outboard engines, it was always in the shop. I finally just gave up and sold the whole thing, and haven't been back in the water since.

Jeff73Mach1 · « **Reply #7 on:** August 10, 2009, 05:04:26 PM »

My first boat was an outboard and I remember letting a mechanic do lots of stuff I would have done on a car. An inboard ski boat is much more like a car mechanically with the exception of the wet exhaust system. Heck, it even has what looks like a transmission and a drive shaft where you can see it.

I suppose I should take a few pictures of my car and post them huh? LOL

Soaring · « **Reply #8 on:** August 10, 2009, 05:24:12 PM »

Better still, enter the Mustang of the Month contest. We need some more cars to vote on.

jethat · « **Reply #9 on:** August 15, 2009, 12:58:51 AM »

Could be you have a HV oil pump and the valve covers dont have good shielding aroung the pvc. and breather. Those stock valve covers have collector value now. I had a set I picked up off a junk engine and tossed them thinking they were worthless only to find out later they sell for 150-200 bucks on e-bay. The timing may bot be as far off as you think. Mine is set at 34 total all in by 3000 and I didnt pay attention to the initial at all. Take a small pipe wrench and gently work it loose.

jethat · « **Reply #10 on:** August 15, 2009, 01:02:26 AM »

Just out of curiosity what did you pay for that car?

Jeff73Mach1 · « **Reply #11 on:** August 15, 2009, 09:01:46 AM »

I suspect the timing really isn't far out at all based upon the way the car runs. I'm out of town and won't be able to work on the car for a week or so, but the shifter won't be here til then anyway.

I agree the stock valve covers should have been retained, but the prior owner made that decision.

As to what I paid for the car . . . that is like asking a woman her age and I will give you the only proper answer Just the right amount

jethat · « **Reply #12 on:** August 15, 2009, 09:35:45 AM »

You may want to consider getting some better ones that have the shielding. My car has a HV oil pump and the covers I have do have baffels around the oil breather/pvc. I still get a little leaking around those areas. Might want to check out a set of Ford Motor Sports covers. They are the best ones..

Jeff73Mach1 · « **Reply #13 on:** August 16, 2009, 07:57:29 PM »

Actually, they are the ford Motorsport covers LOL Just the wrong cap.

Jeff73Mach1 · « **Reply #14 on:** August 29, 2009, 04:34:25 PM »

Just an update, the proper breather cap resolved the problem and I have done some hard driving and some high rpm runs without the least bit of trouble. I also found a proper vented cap that would allow me to plumb the breather vent hose to the bottom of the air cleaner rather than having it just venting to the engine compartment. Pulled it off a junk 351 at the local pull a part and paid about a buck for it.

Still need to adapt my air cleaner base but at least my engine isn't spraying oil anymore.

Soaring · « **Reply #15 on:** August 29, 2009, 04:39:27 PM »

I love it when a project comes to fruition. Good job. These engines have to breathe, and that is something that dumb butts don't know when they buy the aftermarket covers.

Jeff73Mach1 · « **Reply #16 on:** August 29, 2009, 10:30:27 PM »

You said it!

tysonattrell · « **Reply #17 on:** January 27, 2010, 11:43:12 AM »

i got some 351C "Power By Ford" valve covers, along with many more parts including the whole motor, all for sale, just ripped apart for head gasket. anybody know how much i might get for this cleveland? runes good, but could use new rings, got a little blow by.
the motor is currently in my 78 ford pickup.

jethat · « **Reply #18 on:** January 27, 2010, 01:47:47 PM »

Quote from: tysonattrell on January 27, 2010, 11:43:12 AM

i got some 351C "Power By Ford" valve covers, along with many more parts including the whole motor, all for sale, just ripped apart for head gasket. anybody know how much i might get for this cleveland? runes good, but could use new rings, got a little blow by.
the motor is currently in my 78 ford pickup.

Are you sure its a Cleveland and not a 351m? Cleveland's didnt come in trucks. if it is a Cleveland it might make you more money if you sold it off in parts. Rebuild able cores still arent worth a whole lot despite the fact they are becoming some what rare. might be worth $300 unless it has 4v heads in that case sell them separately. There isnt a huge demand for them so it can be hard to find buyers.

tysonattrell · « **Reply #19 on:** January 27, 2010, 01:58:14 PM »

yes it definatly is a cleveland, did some investigating other day, the previous owner put the cleveland in the truck, and yes i'm 99% sure they are 4v heads. how would i check to see if its 4v not 2v heads?

Author Topic: 351C blows oil out of the valve covers (Read 8673 times)

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