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What should I feel at oil filler pipe?

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Jim Lee

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One more question to the group while I am at it. After an excursion I can smell some kind of oily smell and lift up the hood and see a very small amount of smoke coming up from the oil filler hole. If I take off the oil filler cap it puffs out a little bit of smoke and that is that. Is this normal? Is it what is called 'blowby'? I just did a test where I take the cap off and hold my hand a few inches above the pipe at idle. It is a continuous stream of hot air not unlike the output from my little heater inside the cabin. You can feel the rpms of the idling engine which does not surprise me but is this what I should be feeling OR could it be time for rings or ???? I have done compression tests recently, wet and dry, and while it is not up to newly rebuilt standards it was within specs. I will do some more compression testing and report back but I am just wondering if all, or most, of what I am describing above is relatively normal.

Thanks very much,
Jim Lee
 
A leak down test will tell you more about rings and lifters.
 
Sounds relatively normal to me, Jim. As you say, not up to "freshly rebuilt" standards, but quite acceptable. The normal pulsation from the engine running tends to feel like constant air movement even when it isn't; plus you're getting at least some blowby. Actually, even a 'fresh' engine has some, the question is just how much.

But I have run engines that were in an advanced state of wear, and they still ran pretty good. Leaky rings are mostly noticeable as a lack of torque at low rpm.

I bought a TR3A once that had literally been driven by it's previous owner until it wouldn't run any more (apparently without even changing oil), and drove it for most of a year that way. Had to rev to 2000 rpm or so just to get the car moving, and it sounded terrible, but it ran.
 
Jim Lee said:
What should I feel at oil filler pipe?
Click to expand...

Poorer.

I can't believe the price of oil -- not long ago it was almost as cheap as gasoline. Guess I notice it because I have finally run thru my stockpile of cheap oil bought during sales.

Oh, I too have the bit of smoke from the filler.
 
Now for some actual data. Did compression testing and here it is:

Dry Wet
=======================================
1 120 165

2 110 150

3 125 140

4 130 140
=======================================


Hope that formatting behaves. My compression analysis abilities are lacking but I seem to recall that the most important thing is consistency across cylinders.
I would guess that the forum would say that my compression is fairly uniformly low. The only thing close to an outlier would be the wet 165 on cylinder 1.
I also recall reading that a large difference between Dry and Wet would indicate sloppy rings. Do 1 and 2 look real sloppy or just a little. Not to get too scientific :/>. I am going to get me a leak down tester and see what that shows for educational purposes if nothing else.

Have at the data and tell me what you think.

Thanks,
Jim Lee
 
The numbers don't look horrible. Some wear judgeing by the differences between wet and dry. 1 and 2 look worse but the fact that you are still above 100 dry looks pretty good. Some blowby is normal for any engine and even a factory fresh engine just off the dealership floor you will feel a little pressure when you take the oil cap off. New rings only might help but you could get in there and find the liners are worn too. A leak down test will tell you a little more. If it's not blowing clouds of smoke keep driving it. If it is, bring it here and fog my misquitos for me.
 
angelfj said:
Normal, in my opinion since TR's don't normally have valve stem seals installed.
Click to expand...

O Good Twin, how do valve stem seals affect compression?
 
angelfj said:
But, they will prevent some of that oil vapor from collecting. Won't they?
Click to expand...
Not so's you'd notice. When seals are installed, normally it's only on the intake valve guides. Since the bottom of the intake guides are exposed to intake manifold vacuum, there can be oil sucked down the guide, resulting in smoke in the exhaust. But there is nothing to cause smoke in the crankcase.

The pressure differential across the exhaust valve guides is only whatever back pressure your exhaust system causes, so normally there is no gas flow through the guide. I guess if they were really badly worn, you might get some, but I've never seen any indication of such even on severely worn heads.
 
IMO, it's rings.

What is curious is the TR3 has a crank case breather pipe of a size that should not allow for crank case pressure to build up enough to blow by through the oil filter cap. May want to check for excessive sludge build up or a hornets nest in the pipe.
 
Geo Hahn said:
Guess I notice it because I have finally run thru my stockpile of cheap oil bought during sales.
Click to expand...
Something I just recently discovered: Since O'Reilly bought Kragen (actually Checker/Shucks/Kragen but around here they were called just Kragen), they haven't been putting ads in the newspapers. But they still have pretty good sales from time to time.

At the moment (until 10/29/10) you can get their "house" conventional oil for $2.29/qt or full synthetic for $3.49.

Or, 5 qts of Valvoline or Pennzoil conventional, plus a Fram oil filter, for $17.
https://www.oreillyauto.com/site/c/currentad/get.oap

They did have my favorite oil, Valvoline full synthetic, for about $4/qt, but that sale is over.
 
TR6oldtimer said:
What is curious is the TR3 has a crank case breather pipe of a size that should not allow for crank case pressure to build up enough to blow by through the oil filter cap.
Click to expand...
The combined sizes of the passages to the cap are somewhat larger than the road draft tube (especially once you take into consideration the baffles inside the block). And the stock cap is basically open (the wire mesh only catches larger rocks). In addition, the inside of the engine is quite a bit hotter than outside air, so there is actually something of a thermal convection effect with the car stopped.

At any rate, in my experience, it's not at all unusual to find a bit of smoke or evidence that air is blowing out through the mesh in the cap. I wipe away the oil deposited there at every oil change.
 
I guess the TR6 fixed that problem. It just puts the intake manifold vacuum to work on the breather pipe and sucks all the blow-by back all the way to the combustion chamber. And, if you have enough vacuum it may stop the front and real seals from leaking. :laugh:
 
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