[dv657172]

Been to the track twice this year after changing what I thought was a leaking rear main seal from Viton (2 piece) to Best Gasket as car has an Eagle crank with the hash marks.

It appears I am popping out the dipstick at high rpm (5500 shift points) which is spraying oil on plug wires/firewall (see 1st pic) and I have some oil in trans converter cover (2nd pic) although only a drop at the rear of the pan (3rd pic). Also some oil on oil filter and starter bolt. Car doesn't leak just sitting.

Car has a Moroso crankcase/header evac system (MOR-25900) which goes from the front of both valve covers to the header extension pipes, not the headers if that matters. Stock valley pan with a Standard V112 PCV.

Engine only has 20 runs on it, half of which has been an 1/8th mile and that is the only use the engine has had. It was built by a previous owner, only broken in on a stand and then sold along with the car. Car runs near 12 flat in the quarter but normally runs on an 1/8th mile track.

1965 GTO
1968 400 engine with Eagle crank stroked to 462"
Eagle H-Beam connecting rods
1968 #16 heads
BRC (Brooks Racing Component) pistons
Melling oil pump M-54D-S
Stock 68 oil pan with one piece gasket
Unknown cam

While I know it could be a ring issue, would you put money in a vacuum pump or a better oil pan to see if that helps before tearing down engine?

[Sirrotica]

A leakdown, and a compression test would be appropriate before you go investing in other hardware to try to solve the ultimate problem.

Depending upon what rings were installed they may not have completely seated yet. Could be due to bad hone, incorrect bore finish, honing/boring without a deck plate, etc.

The leakdown test will point to where to look for a flaw but will not pinpoint the exact cause.

In my experience with Pontiacs, blowing the dipstick out of the tube is a ring seal problem, you just need to pinpoint the problem that's causing it.

Just for grins, do you have breather oil fill caps vented to atmosphere, or is the oil fill cap a sealed style?

[dv657172]

Sirrotica,

The Oil fill cap is a sealed type.

Compression test from last year, 8 1/8th mile passes ago, was all 155-165.

Planning on doing a leak down test next week

Previous owner apparently planned on building car for street/strip. It is now all strip

[johnta1]

This does it in the 1/8th?

Mine usually did the eight no problem but in the 1/4 it would leak some.
NHRA requires a locking dipstick for this reason, but think it is only required for faster cars? (9.90 ?)

A vacuum pump would probably help, but will need maintenance also.
(draining oil in catch can after every run?)

[Sirrotica]

In round track cars where you're in the gas 2 times a lap, and the races last minutes instead of seconds. They have devised a few different styles of breather systems to minimize crankcase pressure, as well as spilled oil because it can be a fire hazard on engines that the headers and exhaust are red hot. I've had an oil fire, so I never want to see, or be exposed to another one.

After you have satisfied yourself that the ring seal is adequate, you can adapt valve covers with extended stacks with a cap vented to atmosphere, seen here:



The long stacks can have baffles under the tube to seperate the oil from the gases, it then returns back to the valve cover. The closer to true verticle the stacks are, the more efficient they'll be to seperate fluids from gases. Of course these are for a chevy, and as I did back in the day, you have to fabricate them for a Pontiac Stratostreak V8. Back in the 70s I used the breather caps that slid on the filler tubes on SBCs to top the stacks. Out of necessity many years ago we would pull an old cotton sock over the caps to retain any liquids and tie them tight to the stacks Years later they have breather caps with pleated material, similar to cotton gauze air filters, that can be clamped on the end of the stack to keep any liquid inside of the engine, while letting the gases out.



There is also a breather system that attaches to both valve covers at the front with a balance tube, again with 2 breather elements to vent pressure, but not fluids. It would be located over the water crossover. Again, the aftermarket makes them for chevys, but sells kits to adapt this style to other engines, so Pontiac lovers have to fabricate their own system.



When you run an engine at WOT for many laps, the air being pumped by the pistons reciprocating in the crankcase has to go somewhere. Diesel engines also have blowby no matter how good the ring seal is, they also vent it either to atmosphere, or back into the intake tract.

This is how sometimes diesels runaway, the mechanical seal in the cylinders for whatever reason starts feeding oil back into the intake tract, causing the engine to run on the oil uncontrolled because a diesel has no throttle plates. The only way to shut the engine down is cut off the air, putting a board, or something similar over the air intake.

The system you have now in the exhaust, will be marginalized if there are mufflers, due to the back pressure. The velocity in the extension pipe will be higher than in a collector, but there would have to be no backpressure, cancelling the scavenging effect.

One final thought, dedicated race engines do not have dipsticks, the oil isn't in long enough to need checking. One less place you don't have to worry about loosing oil, if you're running on the street, I would likely keep the dipstick function.

[dv657172]

Issue was the evac system, no vacuum. Individual who installed the tubes in the header extensions did so at only about a 30 degree angle (45 recommended) and more importantly did not install them deep enough in the extension. I also did not have baffled valve covers.

I now have baffles installed, new evac tubes installed and definite vacuum at the breathers. You could even here the suction when removing the breathers.

[dv657172]

typo on my part, I meant the check valve. Appreciate the offer

[Johnny406]

Are you running mufflers?

How far from the end of the header extensions are your evac tubes? Depending on the angle, you may need a bit more length to get enough velocity to vacuum out the crankcase.

Have you inspected the rubber hoses from the breathers to the evac tubes for any leaks/header burns?

With your vehicle idling, can you place your breather on your hand and the vacuum holds the breather to your palm? I'll try to take a picture of mine shortly to show what I mean.

[dv657172]

UPDATE

No blowby at the either valve cover breather hole at idle or 4500 rpm

Did a Leak Down Test for a benchmark and had 4-6% leakage at all cylinders except #4 which was 16% and leaking out carb only (intake valve related I assume, its always something )

However, at idle and 4500 rpm both breathers had no vacuum and in fact were pushing air (exhaust) out of them effectively into the engine

Would appear that the check valve on both sides is not working.

Waiting on Moroso tech dept to provide their opinion on whether placement of the tubes into the header extensions rather than the header collector is an issue or not.

[Tim Corcoran]

I have found that the header evac system does not work if running mufflers. The location and angle of the pickup tube is critical for the system to provide enough vacuum to function properly. The pickup tube should be in the collector for best results. How is your header evac system set up? Are you running mufflers? If you are running mufflers, I recommend you do away with the evac system and go with a factory PCV system with vented valve covers.

[dv657172]

Johny406 & Tim

Car does not have mufflers.

DS header extension pipe is 20" in length and PS is 24"
Evac tubes go into extensions 4.5 inches behind connection to header (pic 1 - note car is on jack stands in pic)

2nd pic is how I have system set up at valve covers

["QUICK-SILVER"]

Any chance the lower section of the dip stick tube is MIA?

I would clamp a plug on the tube till you get this figured out.

Clay

[ta man]

Originally Posted by "QUICK-SILVER"

Any chance the lower section of the dip stick tube is MIA?

I would clamp a plug on the tube till you get this figured out.

Clay

If the dipstick is plugged the pressure will try and escape somewhere else. I fought this years ago with an engine with poor ring seal and went to a vacuum pump. Mine is also a street car that I have had zero issues with maintenance on the pump.

[Scott Stoneburg]

I have no experience with header evac systems, but I do remember something about the nipple that the tube attaches to has to protrude into the collector a small amount correct? Is yours but welded to the collector extension flush or does it go in a little?

[dv657172]

Dipstick tube is all present and accounted for. Its the dipstick that is popping out on a run.

[chuckies76ta]

Put a vacuum pump on it and be done with it. 8 to 10 inches of vacuum at WOT will be enough. Seal up all the engine if you go with a vacuum pump. No breathers. Plug dipstick.

[Johnny406]

You don't have a muffler but in the picture it looks like a reducer/restriction at the turn down. I'd clamp the hose, I prefer using the clear nylon reinforced tubing with clamps over heater hose which could collapse. I'd also check the check valves to make sure they are only flowing one way (like a diode)and not two ways. Hose clamps are a good idea as well.

[Tim Corcoran]

My evac system is just like yours except my venturi tube is in my collector and I have no extension or downturn. I have no idea if that would make a difference. When I had 2-1/2 bullet mufflers and exhaust forward of the axle my evac system was ineffective. I have been using heater hose with it for over 20 years and it works fine. My guess is it might be a poor ring seal at RPM but seals OK cranking when you do your compression check. A vacuum pump may work as a Band-Aid to leakage past the rings. Vacuum pumps work great and allow the use of low tension rings on a race only application but I don't think the pump would last very long driving on the street depending on how much street driving you do. One more thing too much ignition advance can cause excessive blow by you might try backing your timing off a couple degrees and see if that helps.

[dv657172]

Johnny406 - the extension pipes are just plain 3" steel with a turndown, no reducer or restrictions other than the non-mandrel bend. Congrats on your PB!

Tim - The car is for race only, no street duty so a vacuum pump may be in my future. In terms of ignition advance I have it set at 15 initial and 35 total at 2,500 rpm, admittedly a quick curve but may lock it out at some point. No VA.

[dv657172]

It goes into the header extension