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TR4/4A TR4A Excessive oil consumption-PCV valve or ??

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r66

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I recently took a 200 mile round trip in my TR4A. Oil consumption was around 1 qt per 100 miles (lots more than last year). Bottom of car is covered with oil from oil pan aft. There is oily film on deck lid and license plate. There is evidence of oil "spray" on garage floor, coming from exhaust pipes. Car starts and runs fine.

The PCV system vents from rocker arm cover thru a PCV valve and then to intake manifold. When running the engine, I observed the hose connected to the intake manifold to collapse (difficult to believe it could seal completely). I replaced the rubber diaphram inside the valve. The plunger and "valve" seemed to function ok. I restarted the engine and the hose again collapsed.

Should I just replace the hose with a stiffer version (existing one comes from Moss- I replaced all hoses 3 years ago) ? I believe oil comes out oil pan and rear seal, but I'm not sure how oil gets inside exhaust as compression is 150-160 on all cylinders.

Any advice appreciated.
thx-R66
 
Failure to relieve crankcase pressure will do that. You might forego the PCV valve and vent the valve cover directly to a carb's air box to relieve crankcase pressure.
I guess there are more than one way to skin this cat, but I'd bet the culprit is failure to relieve crankcase pressure.
 
Also should mention there is no/lvery little blue smoke coming out tailpipe. Exception is when car is cold/just started.
 
See any evidence of oil coming out of the dipstick hole ?
 
r66 said:
Should I just replace the hose with a stiffer version (existing one comes from Moss- I replaced all hoses 3 years ago) ?
Click to expand...
Worth a try. Sounds like the hose Moss sold you was not rated for PCV service; ordinary 'rubber' will soften in just a few years and collapse under vacuum as you have seen. Try finding some "PCV" hose at your FLAPS, it should resist the effect of crankcase fumes for more like 10 years.

Or just punt the entire PCV system, plug off the valve or manifold fitting and hang a length of hose off of the rocker cover fitting. Make it long enough to hang down near the ground and leave the end open. We tried this on a friend's TR6, and it greatly reduced his oil consumption.
 
The parts houses also make a nice short steel spring sleeve that shapes the hoses and prevents them from shutting at the bend.
 
Did not see a lot of evidence of oil leakage at dipstick. Block is pretty clean and freshly painted. Oil seems predominately at oil pan. It always leaked at rear seal too.
 
Hi,

I've experienced similar troubles with PCV on a 1966 TR4A. As Randall suggests "...punt the entire PCV system...". You will know within a 15 minute drive if your problem was crankcase pressurization caused by faulty PCV. My engine is 100% stock. PCV system functioned normally for ~7 years until one day, I started experiencing severe oil leaks caused by crankcase pressurization. I did exactly as he says and it solved all my crankcase venting issues. Now I usually see only one drip of oil after a one hour drive.

I appreciate this post since I never even considered collapsing PCV hoses. I only tried to diagnose the PCV valve itself. Gives me something new to look into! Wouldn't it be great to fix this issue with only a few dollars in hoses?

Bob
 
I thought another solution was to lose the PCV system and install the TR3 vent pipe that comes off the side of the engine (it's the same block) and also use the TR3 vented valve cover cap. Have I got these facts straight as I was thinking of doing this conversion to my 4A after reading about blown seal issues?
 
Karl,

Yes, my TR4A already had a TR4 valve cover and vented oil filler cap already installed with the PCV valve installed when I bought it. All I had to do was install the pipe. The intake manifold will need to be plugged where the PCV connects or swap out the intake manifold for an earlier one.

Scott
 
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