[Fot] Oil Blow-by Cause? More Data but nothing obvious

Sat May 25 12:50:12 MDT 2019

Hi, Paul, good thoughts, but this is exactly the same breather and catch can configuration I’ve been running for the past six years, with no issues.
There was no oil leaking out around the valve cover gasket itself, though it was blowing out these breather holes and the pinhole in the top of the valve cover cap.
Return of oil to the crank - oil flows back from the head through all of the pushrod galleys.  I cannot see how they could possibly be obstructed.
You do bring up an interesting point - is there possibly substantially more flow to the rocker arm assembly all of a sudden?  The only way this could happen is if there were significant wear on the assembly that now allows a huge oil flow.

This was not a problem that was building all weekend.  I have the bonnet open after every race, have a meticulous engine compartment with a dry engine and clean surfaces - this was a sudden change from the last race saturday to after the only race sunday.

On May 25, 2019, at 2:26 PM, Paul Ricco <paulricco at att.net> wrote:

Scott,

When we first bought our car we chased a lot of breathing issues and oil being pushed in strange places.  I ended up fabricating a breather tank so and some custom take-offs to solve our issues.  It allowed me to breath the engine the way we wanted and put the tank where we wanted it.  It has taken a lot of pressure off of the engine seals.

If you do not have a crank breather, then it sounds like the oil has be coming from your valve cover to your catch tank.  Is that a correct assumption?

If so, I have 2 questions:

1.  Did the oil level raise much higher than normal under the valve cover?  Is it possible that something has restricted the oil’s ability to flow from the head back into to crankcase? 
2.  Is your catch tank located lower than the breather take-off?  If it is, then excess oil under the valve cover would have followed the path of lease resistance to your catch tank.

I only ask, because it sounds like for that much liquid to have ended up in the catch tank, the oil level had to have gotten high under the valve cover.

We have friends that run a team that supports about 8 cars.  They honestly admitted to oil level problems being cause by about six people “checking and topping off the oil” before every session.  Pretty funny, that a pro team could have that kind of fun.  I do not think that is your issue.

My curiosity would be think through the flow of the oil, and why did it end up in the can.

If your only breather is at the valve cover, then there had to have been a lot of oil under there.  Why did it not follow the returns and flow back into the sump?

Paul Ricco 

> On May 25, 2019, at 12:36 PM, Scott Janzen via Fot <fot at autox.team.net <mailto:fot at autox.team.net>> wrote:
> 
> OK, I re-ran the comp and leakdown tests.  Replaced a gauge that was reading low on the leakdown tester, so I now trust the results. With the exception of #3, leakdown was almost all piston ring leak-by.  #3 had exhaust noise too.
> 
> 1 - cold leak 4%, hot leak 4%, hot comp 195, prior cold comp 200
> 2 - cold leak 9%, hot leak 12%, hot comp 175, pcc 180
> 3 - cold leak 15%, hot leak 16%, hot comp 170, pcc 180
> 4- cold leak 3%, hot leak 3%, hot comp 195, pcc 195
> 5- cold leak 4%, hot leak 4%, hot comp 172, pcc 190
> 6 - cold leak 3%, hot leak 5%,  hot comp 170, pcc 185
> 
> The leakdown results look good to me and are probably valve related.  I’m used to seeing higher numbers on a season-old motor.
> Compression - I don’t know if the drop on 5 and 6 is normal for cold to hot testing.  What would cause this relative to cylinders with almost no change?
> Plugs - Kas asked about the plugs - When I pulled them the first time, the insulators were very light tan, almost white, with tan electrodes - plugs looked the way they usually look in this motor.  After warm-up, they got darker, but not surprising since it was mostly idle time and nothing under load.  No oil on the plugs.  No visible oil coming out the tailpipe, same color back there as usual.
> BTW, my lap times on the last session were a second off the weekend best, but so were most of my competitors, so the engine still seems strong.
> 
> At this point, unless anyone has more suggestions short of tear-down I guess I’ll run it again as-is.  The oil venting points (two valve cover hoses) have not changed, so there was nothing that would have dumped more oil than usual.  I have no block vent, so nothing to blame there. 
> 
> I could have had a mind fart and run with the accusump valve closed (it’s manual) but when I pulled the car off the trailer there was oil and pressure in the accusump, so I must have shut it off full.  Thus, there should not have been excess oil in the pan.
> 
>> -----Original Message-----
>> From: Fot <fot-bounces at autox.team.net <mailto:fot-bounces at autox.team.net>> On Behalf Of Scott Janzen via Fot
>> Sent: Tuesday, May 21, 2019 10:32 PM
>> To: 'Friends of Triumph' Triumph <fot at autox.team.net <mailto:fot at autox.team.net>>
>> Subject: [Fot] Oil Blow-by Cause?
>> 
>> I just had a great weekend at Summit Point, perfect weather, four days and
>> lots of track time, some quick laps and good racing.
>> After my last session, I noticed some dripping oil as I put the car in the trailer.
>> Got it home to find a half full catch can (1 pint?), and evidence of oil blowing
>> out of the valve cover cap vent hole.
>> Tonight I ran a compression test and leakdown test.  Cold engine results:
>> 
>> 1 - 200 and 2%
>> 2- 180 and 6%
>> 3 - 180 and 9%
>> 4 - 195 and 0%
>> 5 - 190 and 0%
>> 6 - 185 and 0%
>> 
>> Note - I suspect my longacre leakdown gauge may not be reading quite right,
>> as when i have the air side set to 100, the leakdown % on the last three is
>> slightly below zero.  So, perhaps the leakdown on the first three is higher.
>> There was no excess oil until the last session.  Oil pressure is about 50 hot at
>> idle and 65 - 75 at speed, depending on RPM.
>> EGT readings remained in the 1200 - 1250 range across three monitored
>> cylinders at top speed What do i have - failing rings?
>> Any diagnosis or tests you recommend before I start pulling the thing apart
>> would be appreciated.
>> 
>> Triumphs racing - I’m sure I’m missing a few but this is who I remember.
>> TR3 - John Hasty, Henry Frye, John Styduhar
>> GT6 - me, Paul King, Jason Sukey, Jay De Pol until his diff case broke Spitfire -
>> Russ Moore, Marty Sukey, Jeff Govert, Kent Bain, others
>> Tr4 - Mark Wheatley, Allen Goode, I’m missing at least another one
>> 
>> Scott Janzen
> 
> 
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