Inline six oil blowout - need help

[Mark B]

Oil blowout happened after 40 minutes of highway travel. My truck is usually driven short distances, so this was a long high speed run in comparison. I was motoring along when the engine started to sound bad and wheez. I immedialty pulled over and shut it down. There was engine oil on the underside of the hood near the firewall, and on the firewall. Most appeared to be on the passenger side area and the passenger side of the engine toward the rear of the block. No oil showed on the dipstick. I added two quarts and it measured full. The engine started and ran fine. No oil leak was observed when I ran the engine at speed (I had someone to look under the hood while I raced the engine). I drove home Ok without a problem the next day, but at a slower speed off the highway.

This same thing happened a year ago - the last time I drove in a similar way on the highway - but without the visible mess of oil. It just seemed to have disapeared.

I don't drive the truck enough to know if it burns oil. A little probably, the engine is original and runs a little dirty. But it certainly is not a smoke belching pig!

Any idea what is going on to cause this?

thanks
Mark

[Davetopay]

Is it set up with a PCV/breather system?

If it is, is it plugged?

Do you have an oil pressure gauge with a metal tube? Plastic tube?

How much oil does it use in 1000 miles?

Does it normally drip when parked?

Any pics of around the engine and underhood area?

[Mark B]

Dave,

Is it set up with a PCV/breather system?
Yes. It has a PCV valve that is plumbed to the carb or intake manifold (without looking I am not sure which).

If it is, is it plugged?
I took out the PCV valve and it is not plugged. I haven't checked the hose itself.

Do you have an oil pressure gauge with a metal tube? Plastic tube?
It does not have an oil pressure gauge.

How much oil does it use in 1000 miles?
I have not driven it 1000 miles in two years! But I would guess one quart. The oil is changed every year.

Does it normally drip when parked?
It has never leaked oil when parket.

Any pics of around the engine and underhood area?
Regret none. I don't think pictures would show very well where the oil went because the oil was clean, and it has mostly dripped off now.

For some reason I seem to remember seeing (but i am not positive), that when this blowout happened, the dipstick was not in all the way. It certainly was before the trip because I had doubled checked the oil level before leaving).

thanks
Mark

[geezer#99]

If your dipstick was blown out of the hole then it's a crankcase pressure issue. Change out your pcv and hose and clean the breather on your valve cover.
Take a pic of your motor so we can see what pcv and breather set up you have.

[Tyler212]

Idk but my brother had a similar problem with his 83. It looked like it shot all of the oil out of the dipstick it covered the headders, firewall, hood, innerfender on the passengerside. We talked to one of the local guys and he said since he's had so many miles that it could have broke the rings off one piston. Something like that anyway said that the compression the piston normally would have had was forcing the around the piston into the bottom end.

Idk if that was the problem because I wasn't around when he tore the motor down and I don't even know if he did now that I think about it. But I figured I could put it out there and maybe someone with more knowledge on the matter could tell us if the guy was right or not.

[Stock72c10]

Exact same thing happened to me and the solution was easy (and cheap), a new fuel pump. I bet yours is leaking where the fuel pump rod goes into the engine, there is a "diaphragm" that will leak and then blow oil all over the passenger side at high RPM's. The oil comes out of the hole in the fuel pump (I think it is on the front) that is there to relieve pressure when the diaphragm moves in/out. The fan helps spread the oil making it even worse when cruising down the road, it looked like an oil bomb went off.

[jasons]

Originally Posted by Stock72c10

Exact same thing happened to me and the solution was easy (and cheap), a new fuel pump. I bet yours is leaking where the fuel pump rod goes into the engine, there is a "diaphragm" that will leak and then blow oil all over the passenger side at high RPM's. The oil comes out of the hole in the fuel pump (I think it is on the front) that is there to relieve pressure when the diaphragm moves in/out. The fan helps spread the oil making it even worse when cruising down the road, it looked like an oil bomb went off.

I'll second this, the same thing happened to me on the 68 inline 6 I had years ago.

[Wrenchbender Ret]

With the engine running pull the pcv valve out of the valve cover. Put your finger over the end of the pcv valve. There should be a strong suction on it. With the pcv valve out of the valve cover, gun the engine & watch for smoke coming out of the valve cover. If there is you have worn piston rings if it a steady smoke. If it is puffing smoke then you have a bad piston.

[Mark B]

Here are some pics

[geezer#99]

Nice pics Mark. Easy fix. Your oil cap needs to be replaced with a breather type cap. To get the vapors out of the crankcase using the pcv you need to draw in some air too.

[Mark B]

And some more...

There is not oil around the fuel pump area, so it looks to be OK.

There is oil immediated over the PCV valve on the hood, and in the middle of the firewall going over to the heater area. The left underside of the vehicle got oiled, but not the right.

There was a vehicle following me for a long time before I pulled over, and he later said that he found oil spray on his otherwise immaculate car. So I don't think this was a sudden blowout, more like a lead that over the lenght of my 40 minutes on the highway, caused 2 quarts of oil to dissapear.

Does that help anyone?

And by the way, I sure appreciate everyones advice and ideas here. Makes me think I can actually find and fix the problem.

Mark

[geezer#99]

Likely came out of the dipstick tube. I had the same thing on a 350 that I put new valve covers on but neglected a breather. Blew oil out the dipstick tube. Cleaned it up and then it blew out my gasket on the fuel pump next. Almost lost the motor but got to enjoy being towed by my dad 100 miles back home in November in Alberta. No heat either. LOL!!!
Like in the other post. Put a breather cap on it. Easy fix.

[MudBug]

I agree with the breather idea. I bought a truck for 600 bucks that leaked oil. I replaced the gaskets and the fuel pump that pumped the crankcase full of oil.I started the truck up and it started to chock itself out the longer It ran .After turning the motor off, the oil pan made a noise sounding like an oil drum getting hot.I put a breather cap on the valve cover and the motor ran like a champ.I guess its one of those things thats easy to over look.

['68OrangeSunshine]

I had this same problem on my last 292 L6. It would consume about a quart of oil [and I liked Valvoline Racing 30 back then] for every hour of freeway running. Around town it didn't use much oil. [Yes, after about 230,000, I was blowing blue smoke rings if I stepped on it, but that's just age.]
Anyway after I checked eveything. And I was sure I had good positive crankcase ventilation... I noticed the timing mark on the harmonic balancer had been moving around. When I pulled the HB off, I found a 3-1/2" gash in the timing gear cover sheet tin caused by the "walking" on the HB. It was not noticable at street speeds but on the highway, it was blowing out fast. Caused a premature engine failure at only 250,000 miles. Check your HB.

[lakeroadster]

Originally Posted by Wrenchbender Ret

With the engine running pull the pcv valve out of the valve cover. Put your finger over the end of the pcv valve. There should be a strong suction on it.

Originally Posted by geezer#99

Nice pics Mark. Easy fix. Your oil cap needs to be replaced with a breather type cap. To get the vapors out of the crankcase using the pcv you need to draw in some air too.

Originally Posted by geezer#99

Likely came out of the dipstick tube. I had the same thing on a 350 that I put new valve covers on but neglected a breather. Blew oil out the dipstick tube. Cleaned it up and then it blew out my gasket on the fuel pump next. Almost lost the motor but got to enjoy being towed by my dad 100 miles back home in November in Alberta. No heat either. LOL!!!
Like in the other post. Put a breather cap on it. Easy fix.

Originally Posted by MudBug

I agree with the breather idea. I bought a truck for 600 bucks that leaked oil. I replaced the gaskets and the fuel pump that pumped the crankcase full of oil.I started the truck up and it started to chock itself out the longer It ran .After turning the motor off, the oil pan made a noise sounding like an oil drum getting hot.I put a breather cap on the valve cover and the motor ran like a champ.I guess its one of those things thats easy to over look.

IMHO these guys are all correct!

I had a similar problem on my SBC. I had a PCV valve but no breather on the valve cover, instead I had a cap like you have. It blew the fuel pump gasket and spewed oil all over the headers, looked like I blew up the motor. I added a breather, problem solved.

Check the pcv like Wrenchbender outlined, then install a breather. You should be good to go!

That's why it is called "positive cranckcase ventilation", it needs to draw in air via a breather, and suck the vapors out via the PCV valve.

(The other advantage of the breather is if you have excessive blow by and the PCV valve is stuck it will spew vapors out the breather instead of blowing gaskets.)

Good luck and keep us posted!

[Stock72c10]

On mine I have a breather where the red arrow is on the picture (driver's side of valve cover just below filler hole). It used to be connected to the air cleaner to supply fresh air but with my new air cleaner I just used a generic air breather like the picture below and it seems to work well.

[geezer#99]

After you put a breather on it and check your pcv keep an eye out for any other leaks. If you had enough pressure to push out the dipstick any other gasket could have been pushed out too. Like valve cover gasket or harmonic balancer seal or fuel pump gasket or possibly your side covers.

[Mark B]

Stock72C10 - thanks for the reply. The arrow you put in your pic - I have only a grommet in the valve cover hole right now. The hose had to come off because my air cleaner will no longer fit with the power booster I recently installed. I hope to find a small temporary air filter until I get an original snorkel type cleaned and painted. Is there a risk my grommet could get sucked into the engine? Is there a better way to plug the hole?

As soon as I get a chance I will test and check everything as everyone has advised, and I will go out and buy a breather type oil cap.

I thought I might buy a 3 gauge instrument set to monitor critical engine stuff. In the secong pic - that wired sensor (its close to the starter) - is that for oil pressure? Would it connect to an aftermarket oild pressure gauge?

thanks
mark

[geezer#99]

Mark. Your grommet will be fine. The sensor by the starter is your oil pressure sender. It's electric type. If you use a oil pressure gauge that is the fluid type you can put a Tee fitting on there and keep your original one working. An elictrical type replacement would just plug in there. However if you unplug the one that's on there your idiot light on the dash will stay on all the time. A temperature gauge will plug into the sender on the drivers side on the thermostat housing. You have a green wire plugged into that.
For an aircleaner they make a small chrome one in 4 to 10 inch size to work on your carb. Don't run without one.

[Wrenchbender Ret]

If that grommet on the side has a hole all the way through then ventalation is not the problem. You still should have a vent cap & plug that hole.

[pritch]

Yeah-there is quite a few problems that can cause your issue. I had a little hole in a piston one time that caused a lot of crankcase pressure and blow-by.

But I just really wanted to say-Nice Truck!

[Mark B]

Hey Geezer#99
Who makes that air cleaner you mention? I am having a hard time finding one to fit the carb and the six inches (max) between the carb centre and the booster.

[geezer#99]

Mr. Gasket makes them. Get one at your local speed shop or try Canadian tire.
There's a pic of one in the 60-66 section in a post by Rusteeze64GB called carb question.
Small but better than nothing.