I have a 1980 El Camino. (http://unixninja.net)

Major items: 350cid v8, holley 750 double pumper 4 barrel, 350THM-R3 transmission, dual exhaust

The problem: dirty block.

The oil always turns to chocolate, and I change it every 2-4 weeks. I live on a small island - milage is minimal, perhaps 750km a month. But I'm in the caribbean, and it's hot... I have a 4 core radiator and a transmission oil cooler and a good thermostat and an after market water temp gauge. She runs at 80C to 85C, perhaps high 80's under worst heat. It's NEVER gone to 90C. The truck gets both town and highway miles (50/50 mostly).

The 350cid v8 has large headers, and they're close to the oil filter. I've taken to putting tin foil and band clamps over the oil filter as an attempt at heat shields. (Is this a bad idea?)

The oil still turns to chocolate after a week. Even moreso, days (as usual).

The engine runs fine. No excessive knocking, no excessive oil burning. Lots of power and torque. I use Lucas oil stabilizer every 2nd oil change. No slick50 yet.

The transmission is solid, no slipping... new filter, new oil, no excessive clutch material in the pan. It's a THM350-R3 - they're tough as nails (well, only next to a THM400).

My question...

What's wrong?!? :)

Do I need an oil cooler? A remote oil filter away from the headers?

I don't want to cook this 350. A new cam would be cool, but I don't want to have to bore it after a stupid failure I could have avoided.

Suggestions welcome... browse the above mentioned site and contact the admin with suggestions or questions, or (preferably) reply here.

The following details might help:

I have no catalytic converters, and dual exhaust with rather large headers.

Electronic ignition (new.. ignition module, distributor cap, rotor cap, ignition module wiring harness, ignition coil, plugs and wires).

New fuel filter and fuel pump and fuel lines. The fuel system holds good pressure.

14" chrome breather (as per 9" shown in pics on the site).

No fuel return line from the fuel pump OR carb (as since I got it, when it had originally a sickly holley 450 4 barrel carb and chocolate engine oil).

Note: ..... it has a split bore intake manifold. I put a standard bore carb on it. I used an adaptor plate to mount it and some decent gaskets. It doesn't leak in any way, and the oil was chocolate before and after this mod (but it's more of a powerhouse now :)

Symtoms have been constant (i.e. nasty dirty oil) across all mods I've done since I got the truck... A summary of repairs is on my site as well.

Thanks again for your comments.

By turning to chocolate do you mean it looks like a coffee milkshake???
Almost sounds like you have a water leak into the oil pan, oil galley, etc. I've had an experience or two where a blown head gasket allows water into the oiling system and it turns the oil the color of a coffee milkshake. One was due to using a faulty head gasket during a rebuild.

Well, after reading your comment I had a close look around the block and noticed there's a little bit of an oil leak around one of the head gaskets. :cry:

The coolant looks good, so I don't think it's mixing with the oil (?). Perhaps its sucking in dirt somewhere?

I guess I've got to get that fixed and see what happens.

Definitely sounds like a bad head gasket to me....

I should add that the oil is turning thick and a heavy dark color, almost black. Normally I'd associate that with excessive heat or just running the oil too long. But I change it at least every month, if not twice a month. And as I mentioned, the water temp is fine (80-85C).

The oil is not foamy or discolored lighter than one would expect, it just goes thick and dark really fast.

Perhaps it's time to pull the covers off the valves and they have to say about the situation. :?

I think I'll also clean up the block and see where the leak really is. I (just) looked again at it and I'm not entirely sure where the oil leaked out and where it ran afterwards...

Thanks for your comments.

Sounds to me, like the second ring on the pistons has excessive gap now. Generally, it is my understanding, that the 2nd rig helps control Blow-by seepage into the crank case. When this happens it dirties the oil. The degree of that depends on the amount of blow-by that is leaking down into the crank case. From your description you have excessive blow-by leak or just bad or worn rings. If the Oil rings are doing their part then you might not see consumption of oil. It doesn't take a lot of tension for the oil rings to work.

Pull off the PCV from the valve cover when the engine is up to temp and look for a lot of "steam looking" smoke coming from the valve covers. Also look at the hose going into the breather see if it is building up a lot of oil in the breather housing, if you have yours hooked up. If not then look into the bottom of the intake or around the base (inside) the carb to see if you have a lot of black oily looking deposits.

If you are not running a PCV or removing the excessive blow-by using a breather cap then that is the problem.

Just a thought.

ElkyPete you are correct... there is no PCV valve from the valve covers.

So what now... take off the valve covers, clean up the mess, find a drill, make a hole, and get a PCV valve for it?

My breather is sort of 'open' - there's nowhere to bring a return line from the valve covers - should it just be vented with a PCV valve and not return anywhere?

You can go get some valve covers with a pvc hole & run it to the large tube on the front of the carb. I have a pvc valve on one cover & a breather in the other.

You need that PCV. You have a couple of options. Buy some valve cover with the hole already, use the filler hole on the opposite side, or drill a new hole and add that PCV.

The engine needs to vent it will make a world of difference as far as Oil condition, combustion, longevity, fuel economy etc... It will also help you keep the engine running and last way longer. Most engines now days have two methods of crankcase ventilation. One is the everyday PCV valve. The other is a vent tube running to the breather or air plenum (EFI). So the engines get vented from both sides. All the actual PCV valve does is block, to a small degree, large amounts of oil from being sucked into the base of the carburetor. The tube they run to the breather had a small filter at the breather, usually to keep out the main flow of oil into the top of the air breather.

Old cars used a Blow by vent or draft tube. The SBC like the 327, 283 etc... had a tube at the back of the intake that lead down to about midway on the bell housing. It would act like a chimney the force of the air passing the engine compartment would help the drafting. The PCV is a better way it always has vacuum on it were as the draft tube only had vacuum when you were driving if you were stopped it vented but not well.

Good luck with that.

P

Duh.

There was a breather on one of the valve covers that was full of 'goo'.

So I got a new, larger one. It's the sort you see on these riced up 4 bangers... only because of parts availability. It's about 3" diameter and about 2.5" high.

But, I have to say, it doesn't look bad on the chrome valve covers next to the new holley 750cfm 4bbl. And now it's not near as stinky, but you can see 'exhaust' from under the hood when you stomp it. However, as a bonus, the oil doesn't dirty as quickly. It's getting some decent ventilation.

But, this means the 350 is sick.

I know now (after your comments and further reading) that I am in fact suffering from excessive blow-by.

The breather helps. So does Slick50.

But in the end, it means she has to come apart.

Sad, and perhaps something that can be delayed for another 12 months, but an inevitable end nonetheless.

Perhaps I should order up a crate GM 454. :D