weird question

[James Hill]

Ok here we go, have a 1952 8n side mount, 12 v
have 110 thru 125 compression 1 thru 4, have blow by coming from the oil fill to the point it drips steadily, when cold it has 25-30 lbs of oil pressure, when hot drops ro 15lbs,get oil on plugs 3 and 4 very wet, 1 and 2 dry, have changed the oil 4 times since january, the reason is because within weeks of change the oil turns solid black and is real thin, then the oil pressure drops to 5-8 lbs when hot, is there any thing else I am missing that would cause the oil to thin out and drop pressure and cause smoking and blow by, other then failed rings, compression is really good for blown rings..

 

[Dell (WA)]

James.....are you remembering to TURN-OFF yer under the tank glass fuel valve when yer done tractoring???

Sometimes the carb float valve don't seal well and gravity will leak 24/7 UP yer intake manifold into enny open intake valves and down past the rings into yer oilpan. Oil diluted with gasoline won't hold pressure and will foam out the filler cap.

As a general rule, 125psi is "braggin' rights" .......Dell

 

[r geiger(oR)]

I would be thinking worn valve guides.

 

[James Hill]

yes always turn it off before i shut the engine off, let die as the carb runs out of fuel, there is no smell of gas in the oil, just burnt.thats whats got me fumbled, good compression, lots of blow by, and smoke, have to choke it to keep it running smooth under load, 1/4 to 1/3 choke. motor has noise, sounds like a rattle from a piston pin to push rod connection.

 

[Dell (WA)]

James........in this HOT WEATHER, 10-30w oil is TOO THIN and will also cause the knocking complaints. Use at least 40-wt detergent. 10-30 is really 10-wt oil. .......Dell

 

[RichMac]

Can one have serious blowby and hence, oil dilution and still have high compression readings if the combustion chamber is clogged with carbon which increases the compression ratio??

Just a thought. I do not know the answer, but it seems reasonable.

 

[James Hill]

run castrol 20w50 with lucas, takes about 4 hours operation for the blow by and smoke to get bad and the oil to turn coal black and run through my fingers like water, check compression right after oil change and again when it gets bad, not much difference 1-3 lbs comprssion differences.
could valves allow oil to get into the compression chamber and foul the plugs and burn the oil and allow it to circulate back to the oil pan?

 

[JMOR]

(quoted from post at 22:30:48 07/06/09) Ok here we go, have a 1952 8n side mount, 12 v
have 110 thru 125 compression 1 thru 4, have blow by coming from the oil fill to the point it drips steadily, when cold it has 25-30 lbs of oil pressure, when hot drops ro 15lbs,get oil on plugs 3 and 4 very wet, 1 and 2 dry, have changed the oil 4 times since january, the reason is because within weeks of change the oil turns solid black and is real thin, then the oil pressure drops to 5-8 lbs when hot, is there any thing else I am missing that would cause the oil to thin out and drop pressure and cause smoking and blow by, other then failed rings, compression is really good for blown rings..

ou have compression rings and you have oil control rings.

 

[old]

I would do 2 things to it. #1 is run a straight weight oil like a 30W or 40W. #2 I would fill the cylinders with ATF and let it sit over night. If you have sticking rings or a real bad carbon build up on the rings the ATF will help. And you can also run it with 1qt ot ATF to every 5 gal. of gas which will also help free up sticking rings and clean up the engine. But if you want to go the high $$ way do that with MMO

 

[r geiger(oR)]

With worn intake valve guides the engine will suck in oil fouling the plugs. worn exhaust valve guides allow some of the exhasut gases to go past the valve into the crankcase.

 

[James Hill]

last month I ran mmo thru the cylinders for 4 days, every day I would add more and turn the motor over to run up the cylinder walls, then add more and let it set till the next day, after the 4th day I changed the plugs and changed the oil and filter.

 

[James Hill]

Then you think I need to ring it, which would mean and overhaul , go that far I may as well put new bearings, pump, and all in it...

 

[James Hill]

can one replace the guides without doing a major overhaul?
trying to hold off rebuilding, unless absolutely necessary, no time right now, no money either really,

 

[old]

Ok then it is time for a 30W, 40W or if your where it is say 80 plus out a 50W oil at least for the summer. I run a 60W oil in my 1935 JD-B because it smokes bad but it also has been since some time in the 40s since it has had any engine work done to it

 

[JMOR]

(quoted from post at 23:14:36 07/06/09) can one replace the guides without doing a major overhaul?
trying to hold off rebuilding, unless absolutely necessary, no time right now, no money either really,

would not put my money on valve guides being the source of oil burning in this particular flat head engine. Look at the oil source for the valve stems/guides. Now if it were a OHV design, that is a different bet. Just my 2 bits.

 

[r geiger(oR)]

the head would have to come off. then yu can check to see how much side slop the valves have before you replace guides. should also grind valves and seats with new guides so may best be part of a overhaul. the part about having to have the choke out to run smooth at power is strange. has anyone ever put a vacum gauge on one of these machines?

 

[Dunk]

This is a Ell of a topic!!!

Man at the conjecture!!!!!

I'll try to re-visit this in the AM.

 

[Bob]

JMOR, you are 100% correct. Worn valve guides are WAY down on the list of possible problems.

 

[JMOR]

(quoted from post at 00:33:48 07/07/09) JMOR, you are 100% correct. Worn valve guides are WAY down on the list of possible problems.

hanks, Bob. I was pretty darn certain, but left myself a tiny bit of wiggle room. As I see it, the lifters only get splash lubrication from below & then that oil would still have a couple of inches to travel upward to get to guides inside the reasonably stagnant area behind the valve covers.

 

[souNdguy]

I'd look at oil control rings for the wet plugs.

as for thinned oil.. might be a leaky carb float valve if you forget to turn gas off.

I think I'd re-ring those wet ones, and drop in new bearing shells, and see what i had. perhaps check oil plunger spring at the front of the engine as well. might be a cheap fix for a couple rings, shells, spring, and head and pan gasket..

soundguy

 

[Tractor,Tractor]

Test

 

[Bill Longstreet]

I had a problem just like that. I would turn off the gas every time. I found out the even when the gas valve was off it was still leaking by and going in to the oil. I got a new gas valve from tractor supply and it did the sane thing. I called Just 8ns and ordered one from them and the problem went a way.

Bill

 

[Anonymous-0]

In your description of problem you left out how she runs,smokes,needs choke,pulls under load.But I think your carb is gummed up.A sticky float can cause a lot of problems,also stopped up passages can told gas tanks have alot of rust in them and can cause problems.

 

[Walston]

The thinning of the oil is interesting, it almost has to be gas thinning it out. Maybe the smell get vented out the fill vent. I can't think of anything else that would thin the oil without making it milky. I disconnect the fuel line at the carb and make absolute sure the shut valve is not leaking. To me it is the only thing that explains all symptoms.

Gas thins the oil get blowby, wet valves. I think this would smoke somewhat as well.

Sticky float - need choke under load

Interesting problem...........

my 2 cents

 

[jon]

yes always turn it off before i shut the engine off, let die as the carb runs out of fuel,

Just for the heck of it, turn off your gas, take the gas line loose from the carb & wrap a small rag around it or prop a jar under it. Betcha somethings gonna be wet in a couple hours.
Too many sediment bowls just "barely" leak but you may not notice it for a while.

 

[Anonymous-0]

Take your carb apart,check your filter in the elbow.check float valve blow out all passages with compressed air.I'll bet she's blowing out what you think is oil out the tail pipe,but i'ts really unburnt gas.Sounds like your motor is flooding itself to death.Might just run like a new tractor when you get your carb right

 

[beal]

hello folks, if i unhook the gas line from the carburator should there be a continuous stream of gas or spurts of gas every 5 seconds or so? thanks.

 

[jon]

if i unhook the gas line from the carburator should there be a continuous stream of gas or spurts of gas every 5 seconds or so? thanks.

Should be a steady flow. You've got 2 screens above it that may be clogged up. Might as well get the one in the carb too while you're at it.

 

[rlpintx]

Where are you getting 50 & 60 W oil? I cant find any and could use some to put off my overhaul for a year.
Thanks
rlpintx

 

[old]

O'reilly's auto parts store have Valvoline racing oil in 30W, 40W, 50W and 60W. Cost a bit more but when you burn a qt an hour I guess it is worth it

 

[jon]

Where are you getting 50 & 60 W oil?

Some motorcycles & small airplanes use 60wt also if you've got either nearby.

 

[gahorN]

(quoted from post at 19:12:14 07/09/09) Where are you getting 50 & 60 W oil? I cant find any and could use some to put off my overhaul for a year.
Thanks
rlpintx

Any local airport carries AeroShell in SAE 40, 50, and 60. Great oil. I use it in my '34 Harley 74 cu in V-twin. You can probably also get it from most local oil suppliers.

 

[jon]

I use it in my '34 Harley 74 cu in V-twin. You can probably also get it from most local oil suppliers.

That's how I got turned on to it, ran it in a 74ci Harley. I've still got half a case of it around here somewhere. Also ran it in my 49N oilburner.