Big white smoke , all RPMs.... Advice?

[pinzton]

[Note: re-posting as it's own thread; to keep the conversation clean : ) ]

I might be in a similar situation to the post 'Big smoke, big oil mess, big problem! Advice/confirmation..

Context:
- I bought a 712m after it's engine was rebuilt 3 years ago; it had perhaps 500 miles since then
- Drove it 20 miles, then HUGE white smoke coming out of exhaust at all RPMs
- Oil level was SUPER low; I refilled it. It keeps it since then (but not driving much except for trial if it's still blowing white)

To check what's going on, this is what I did:
1) I wiped clean all pipes, and oil spills. And drove it for a little bit.

2) I checked the Oil breather (from cylinder 4); it's clean

3) I checked compression on all cylinders:
#1: 178 psi
#2: 178 psi
#3: 178 psi
#4: 176 psi

4) I checked the spark plugs
#1: clean
#2: light, no oil
#3: Dark + LOTs of Oil
#4: Dark + Oil

5) Exhaust connections:
>> I found oil drips; on exhaust connection from cylinder 3 and 4. Oil is found at cylinder 3 near Sparkplug; and bolts

#1: clean
#2: clean
#3: oil drops, near bolt & sparkplug; and on connection
#4: oil drops near bolt & sparkplug; and on connection

6) Valve covers, look from outside (have not opened yet):
#1,2,4: seem good
#3: the valve cover gasket seems to be off on it's lower right side

It has a Weber carburator, not sure if the settings are right, or if it runs SUPER rich (and thus the white smoke)?

Attached some picts (in https://www.dropbox.com/sh/mjnisxq2vr3b ... Izgg9afkqa). Happy for all advice.

[pinzton]

[ Pasting previous replies from other thread here: ]

undysworld:
When oil is sucked up into the intake, it reaches the rear carb first, so I suspect that's what's happening and why you see it in the 3&4 cyl's only - it hasn't reached the front carb yet. I suspect that if you remove the airbox, it will have oil in it.
The truck can inhale and burn a lot of oil rapidly, if the intake is blocked or restricted.

GRCameron
Perhaps this could be tried as a diagnostic...

Remove the ventilation hose (p/n 900.0916/07). and cap the inlet nipple to the air intake where the hose was. Leave the hose fitting on the oil fill pipe open or route it away from the engine through a long hose. This ventilates the crankcase to atmosphere and precludes any oil making it into the engine through the carbs. Run it for awhile and see if the white smoke clouds go away. A few hours of crankcase emissions making it to the atmosphere will not cause major trauma to the environment.
(My '06 Dodge Cummins has a factory road draft tube...)

Jim LaGuardia
Check 3 things in this order, (1) with air box off carbs, look down rear carb throats wile running, if it drips, the the float valve is not seating. Excess fuel washes out the rings. next steps require tear down, (2) check for out of round cylinder, cylinder scored, fractured piston, rings not seating. (3) very bad valve guides
stock ring gap is .5mm-1mm

[pinzton]

Update / additional info:

- Carburetors on the Pinz are Weber, 36DC NVA 18.
(This was an upgrade by previous owner. Not sure if this makes a difference, or only introduces complexity in looking for the problem)

- The Airbox is clean

- I opened the Cylinder head covers:
My observation shows O-rings on the oil return tube are decreasing in quality from 1 to 4 (see picts). Could this be something / indicate a O-ring / Oil return tube replacement?

[mopar]

Is this the truck in question?
http://www.expedition-imports.com/produ ... rades.html

http://www.ebay.com/itm/1974-Steyr-Puch ... 052wt_1186

Vehicle Identification No: 4750793

Does it have the 2.7 upgrade?? I had looked into that truck but never actually seen it running or had itchecked out in person.

[pinzton]

@Mopar: Yes, it's that truck. It's actually in really great condition; everything new and rebuilt. The 712M didn't move much since rebuild, perhaps 500 miles in total over last 2 years. I guess, some seals hardened?

[mopar]

Yeah alex had told me it didn't have many miles on it too bad he never got back to me. Looks like you got a very nice truck a lot was done to it I was told it had a rare boot that went over the fan to keep the noise down never saw one post a picture of that if you get a chance. Hopefully you get it sorted out shortly and its just from sitting and nothing major.

[captxmas]

Sorry to but in but......If you do have a pic of the boot over the air intake to lessen noise I would love to see it. Please post or PM

[pinzton]

@mopar, captxmas: Will post once I have truck back (it's at the garage for checkup)

[pinzton]

ok, riddle solved. Two of the 4 pistons were bad (see pict). New ones are in the making.

Question to the community: I wonder how this could have happened? The car's engine was completely rebuilt; and not driven past 500 miles after that (over 3 years). According to the tech shop, some dirt got to the pistons and srewed things up. Not sure if that's it. I want to avoid that I'm not overlooking another issue that led to this prob.

All ideas/thoughts are welcome!

Thanks, Sacha

[GRCameron]

Was your engine rebuilder familiar with air cooled engines? Piston clearance needs to be greater in an air cooled engine to prevent scuffing like you've experienced. Also, were the pistons oriented properly at assembly (mark on piston crown faces flywheel)?

[Jim LaGuardia]

First, what brand are the pistons and second what was the clearance spec?
Lack of clearance is main suspect.

[Stekay]

I agree with GRCameron & Jim L. You need to do the math! The pistons also need to be 4032 aluminum, not 2618. Here are the coefficients of expansion for each.
4032 AL 2618 AL Cast Iron (cyl)
0.0000112 0.0000129 0.0000058

These are in inches/inch/degF Figure on ~ 175 deg increase in temp from room temp so 240. You'll appreciate where that little bit between the 4032 & the 2618 can be the difference between clearance and seizing.

[Stekay]

Do you have a pic of your cylinders? Also fill in your profile as to where you live.

[pinzton]

Thanks for all the replies; and insights! I'll see to get the pictures of the cylinders from the engine shop LJ's machine napa

I understood it was the 2.7L upgrade kit from Expedition Import. They're Ross Racing pistons. I don't have experience with the Kit, but I would think the cylinders that came with it would have had to be to spec - no?

Unfortunately, it's difficult to trace back WHO did the engine rebuild because it was long time ago. What I learned was the rebuild was done 3 years ago(?), and the truck stood in a garage not having moved much, perhaps 500 miles total since rebuild. I bought the truck just recently 2 months ago. Everything else looks in mint condition.

(Thx Stekay for the profile reminder; I'm quite new here and still figuring things out Profile just updated. I'm located in Sausalito, CA aprox. 40min drive from EI .

[captxmas]

Once again , a little off topic but if you have pics of the engine shroud(?) you designed for noise reduction, I would love to see them.

Thanks in advance.