The end of last season this happened once. Tonight it happened twice. My vacuum pump filled the breather bottle and it sprayed down the motor and front of my car. It happened late in the night when the air was cooler and better. I do a burnout on a rev limiter and I do tend to do an aggressive one. I did not get a chance to watch the gauge, but I don't believe its pulling excessive vacuum. What could be causing it to fill the bottle after just 1 pass? It looks like a mix of alky and oil so I can't say its mostly fuel or mostly oil. Thoughts?

I know that you said this was after just 1 pass? but I want to double check that you are draining the puke tank after each pass. The humidity can play a big role in how much moisture the vacuum pump is able to pull

We place a sweat band (one like an athlete would wear around their wrist or forearm) around the breather to prevent any spewing if we forget to drain it

My dads car does this once in a while. We have a sock around his breather. Make sure.to.drain it as mentioned, but you can also add a piece of rolled up scotch brite pad up inside the breather to.help stop the filter.getting saturated. Also.double check your vacuum.setting

Vacuum leak is first suspect, not draining the puke tank, or oil level is overfull. Could be you've also lost ring seal during that pass.

Moroso sells a black two piece fitting that is mounted in the valve cover, that fitting connects to the suction line leading to the inlet side of the pump. The fitting is designed to draw vacuum but reduce the amount of oil drawn into the inlet side of the pump. Before I installed this ($44.57) fittting from Moroso I also used a athletic wrist band to contain the oil from overflowing out of the puke tank. That did not reduce the amount of oil drawn into the tank it only reduced that amount of oil blowing out of the tank. I still had to drain the tank every two runs, then check the oil level in the pan. The Moroso fitting ended the problem, at most I get a small amount of oil collecting in the puke tank but enough to lubricate the pump. Using the Moroso fitting there is no need to drain the tank until I’ve made at least 15 runs. I drain the tank before each event, never during the race.

Also:

Moroso also sells a 30-0 vacuum gauge (89610) for $32.99 to monitor the amount of vacuum drawn by the pump. Jeg’s sells a similar gauge (41009) for $19.99. A RacePak data recorder can record and store the vacuum amount while it’s difficult, if not impossible, to watch a gauge during a run.

FYI: Everyone I have spoken with recommends not exceeding 14 pounds at full throttle.

Bob

Okay if you are getting that much stuff in your catch can then most likely you have a vacuum leak on the motor.
What that does is allow the air to go through the motor pulling oil with it. When system is right the pump is pulling a vacuum but not much VOLUME of air. Now another possibility which I doubt is the rings could be passing a bunch of air.

Bottom line is too much air going through the vacuum pump system. I had same problem big time and resolved it by sealing motor good. Around distributor, valve covers, crank seals, oil pan, intake and timing cover. Any place air can draw through under a vacuum.

Note, that is same reason I recommend you do not put the safety valve on the motor. Because when it reaches its setting then it opens to allow AIR to draw through motor. Put the valve on the pump.

Something fishy here. Could be the fitting where the vacuum is drawn or ring seal issue. Might want to leak it down to find out. My puke tank will have 2 or 3 DROPS in it after maybe 25 runs or so. Pulling 13" at speed. JB

Thanks guys. I'll check things over Thursday when I get to the track to prep for the weekend. The car was fast and very consistent all night and ran the same a few weeks ago so I doubt it's a leak, but I'll certainly check it out! I'll let you know if I find something.

I am pretty sure you have a leak. When you have an air leak air blows through motor taking oil with it like crazy. Been there done that and made one heck of a mess. Sealed it up better and never have any issues.

I was filling the bottle each pass for a while.

First, I found an air leak at the base of the slip collar distributor. Fixing this helped a good bit but still too much.

Secondly, I turned the vac down to 9-10". This helped more and, while still too much got in the bottle, I can live with it.

Thirdly, I usually only bring this car out to run Super Comp. I decided to bracket race it on the 1/8, and was hardly getting anything in the bottle.

Looks like the #1 issue now is that the heads aren't draining the oil back fast enough.

I'll check for the leak first thing. One last question. Any chance doing a longish burnout on the rev limiter could be affecting things as far as this issue goes? Like maybe it's super rich on the limited and it's getting in the oil more at that point?

I do not think the long burnout did it other than a longer time sucking oil into the canister.

If you can find a vacuum pump you will be surprised where you find leaks. I had leaks around timing cover and distributor collar. We put some RTV around the outside of the timing cover once we found the leaks and it took care of most of it. Now I pull 17.5 inches of vacuum. Going to drop it down to around 14 next race as it does not need that much.

Really only two ways to fill the puke tank.

Rattling the rings is one, and a very bad one to do!

The other are vacuum leaks, and they occur EVERYWHERE! A smoke machine is the easiest way to find them. You will be VERY surprised at where these leaks can show-up! The leaks let air go through carrying oil and filling the tank.

The vac regulator in the wrong place can also cause issues.

I went from needing to drain my puke tank every 3 runs, to draining it once every few races by replacing my valve cover gaskets that looked fine. If your fitting is in the front of your valve cover, the pump may sometimes get a big "gulp" of oil if you get on the brakes hard at the end of the run and all of the oil in the valve covers sloshes forward.

What the other guys are saying is exactly right. I deal with this every day.

For a breather tank to have oil in it, you either have a lot of oil up in the valve cover, or you have your fitting positioned incorrectly.

The worst place to fully dedicate the inlet line of your vacuum pump, is in the valve cover. Use the vacuum to your oil pans advantage, and not against it. A vacuum pumps inlet line is no different then a "black hole". If you want your oil to be suspended in your valve cover, then place the fitting "black hole" at your valve cover. If you want your oil to come down, and your valve covers to remain with moderate to slight oil in them, then consider relocating that vacuum to the pan.

Oh no.......did he just say "put the inlet line at the pan" ? "he must be living in a cave, because he sure hasn't witnessed what everyone does, and that's to have the vacuum pumps inlet line at the valve cover. The majority do it, so it must be correct.

" the pan, hell no, then it will really fill my tank up and puke all over"

Really, as in you tried this method?

you know how that say'n goes in business "location, location, location"

I tried it on the fuel pump block off on a BBC dry sump engine once. Filled the puke tank very fast. Maybe it would work if you put it in line with a cap like where we put our drain back lines. Never have tried it though, or seen anyone try it.

quote:

tried it on the fuel pump block off on a BBC dry sump engine once. Filled the puke tank very fast.

Did you block off the fuel pump pushrod hole? Did you enlarge the access hole in the block leading to the pan? Did you place the fitting high on the block off plate? Do you click neutral and shut the engine off right after the stripe?

After years of experimenting and hearing results from my customers, I gotta say that Strange Magic is the only one who has successfully used the oil pan as the suction point for a vacuum pump on a wet-sump motor. How do you keep the oil away from the suction point? Even if your motor is well-sealed, you have leakage through the rings, Etc. Every engine I've ever seen has some amount of blow-by, so air WILL be moving through the pump, taking oil with it, if oil is present.

quote:

Did you block off the fuel pump pushrod hole? Did you enlarge the access hole in the block leading to the pan? Did you place the fitting high on the block off plate? Do you click neutral and shut the engine off right after the stripe?

No did not block off anything or enlarge anything. Was just experimenting with it. The fitting was towards the top of the plate. This was idling in the garage when it filled the puke tank, after that I aborted that idea.