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Resolved 2G MD184946 & MD305709

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GSXRunner

Proven Member
160
36
Feb 24, 2013
Queens, New_York
I was losing oil through that plug seal (MD184946) at the end of the intake camshaft. After doing a boost leak test, the cap completely popped out. I'm thinking, if I put it back in, it's going to eventually pop back out again.

After looking at the part in an exploded view diagram, I see another part (MD305709) that is supposed to be installed over the plug seal (I'm assuming) to keep it from popping out; it has two bolts that go in the side of the head. Well, I'm missing that part and I can't find a source for it.

I've torn this head apart several times and I've never seen that part before; didn't know it even existed. I don't remember ever having an oil leak at this point, but I built the turbo and I know there is a lot more boost now, so that cap doesn't want to hold the pressure.

Do I have to fabricate this part myself?
Is anyone else running their engine without this piece?
Do you know where I might be able to get one?

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Does your motor have excessive crankcase pressure? Does it pop the dipstick up or out also?
 
I am just trying to figure out why it popped out under a boost leak test. :hmm:
 
It was already very loose. I heard a small hiss coming from it, so I pushed on it with my fingers and it popped off. Anyhow, do you have any answers to my original questions?

Bad PCV maybe?
Looks like you could use a 1G CAS to seal it off.
Nope, it's not the PCV. There is always going to be air going through the open intake valves, through the piston rings and into the crankcase. This is normal as piston rings don't make a perfect seal and I don't have a blowby problem, trust me.

I have some flat bar, I'm thinking of making something to bolt over that seal because no one seems to know anything about this part.
 
The seal that has rubber around it appears to be the block off seal for a motor without balance shafts. I have never seen one in the CAS spot but I am sure it has probably been done. As Steve stated, you could put a CAS in there and it would never blow out (since it is held in with 2 bolts) and would seal, you just wouldn't use it.
 
The seal that has rubber around it appears to be the block off seal for a motor without balance shafts.
Why should it have anything to do with whether you have balance shafts or not? The balance shaft is in the block, this seal is in the head.

I have never seen one in the CAS spot but I am sure it has probably been done.
It is the stock setup for my engine. My CAS is at the other end of the camshaft.
 
That seal looks just like the seal that is used in the spot where a balance shaft would go on a BSE is what I was trying to convey. I, myself, have never seen one used in that spot but if you have enough pressure to blow it out, I don't believe it was meant to be there (but I only have 1g DSm's, no 2g's).I assume a 2g is what you have, but you have no profile to view. http://www.dsmtuners.com/dsm-profiles/add
I was able to pull up a picture with a 7 bolt and it does have a rubber plug. If you were able to fab a strap for the CAS bolt holes, that should hold it in. It still doesn't explain why it blew out other than crankcase pressure. Our 1g units have the CAS that bolts in so it CAN'T come out (hopefully).
 
You already have the part numbers, why not just buy a new seal and plate? You also need two bolts for that plate: MF240051
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Thank you @dwb !!!!! :thumb:
He was just missing the hold down strap.
 
if you have enough pressure to blow it out, I don't believe it was meant to be there
Well, that piece MD305709 is meant to be there covering it so it doesn't blow out. That is why I asked the question in my first post.

I assume a 2g is what you have, but you have no profile to view. http://www.dsmtuners.com/dsm-profiles/add
I thought I filled all that out a long time ago. Yes, I have a 2g and it's a GSX as hinted by my profile name. I guess when I have time I'll go through it again.
It still doesn't explain why it blew out other than crankcase pressure.
Well, when you pump a steady pressure in through the turbo with some intake valves open wide, you're going to get different pressures than you will naturally from a running engine. That plug could be worn out or maybe I didn't install it correctly. However, there is a piece that I'm missing (MD305709) that is supposed to hold it in place. I would think that if it couldn't come out without that piece, the piece would never have been part of the system.
 
Well, when you pump a steady pressure in through the turbo with some intake valves open wide, you're going to get different pressures than you will naturally from a running engine.
How do you get enough positive crank case pressure that it pops a seal? An open intake valve (or exhaust) by it's self does not inherently create crank case pressure during a BLT. Only if you have serious blow-by or your PCV system is not functioning properly would you get positive crank case pressure during a BLT. Do you have a CC breather on your valve cover?

You have at least two problems here. A missing plate and too much positive crank case pressure. Those may be exaggerated by a bad seal and a blocked CC breather.
 
How do you get enough positive crank case pressure that it pops a seal? An open intake valve (or exhaust) by it's self does not inherently create crank case pressure during a BLT. Only if you have serious blow-by or your PCV system is not functioning properly would you get positive crank case pressure during a BLT. Do you have a CC breather on your valve cover?

You have at least two problems here. A missing plate and too much positive crank case pressure. Those may be exaggerated by a bad seal and a blocked CC breather.

That missing plate was the culprit for the seal coming out.
As for the pressure, Steve and I tried to express that. In my 40 some years of building motors, the pressure inside shouldn't be that great on a good/fresh motor. On these 4g motors, the valve guide seals and the guides themselves tend to let pressure out/in more than other models of motors (GM, Ford...domestic stuff) when they are worn.
 
How do you get enough positive crank case pressure that it pops a seal? An open intake valve (or exhaust) by it's self does not inherently create crank case pressure during a BLT. Only if you have serious blow-by or your PCV system is not functioning properly would you get positive crank case pressure during a BLT. Do you have a CC breather on your valve cover?

You have at least two problems here. A missing plate and too much positive crank case pressure. Those may be exaggerated by a bad seal and a blocked CC breather.
I had my breather blocked off. When I was testing, I heard a leak from it so I mistook-en it for a intake side vacuum line and plugged it up with a bolt (doh!), not realizing that I was effectively pressure testing my crankcase. I guess with all the heat and humidity, I'm making newbish mistakes.

The weakest link blew out and that was the cam seal. There is nothing to hold that piece in other than that bracket which I'm missing. It's just a friction seal. I ordered a new seal and plate. Thanks for reminding me about the breather.
 
That plate is the mount for the 2Ga knock sensor connector. While it may help keep the seal from popping all the way out, its function is not to help the seal stay seated. As stated, it's either an old, hard seal or you've got excessive crankcase pressure. Using it as a retainer is putting a band-aid on a different, potentially bigger problem.

Also: 2G - Want to play, where does this go?

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That plate is the mount for the 2Ga knock sensor connector. While it may help keep the seal from popping all the way out, its function is not to help the seal stay seated. As stated, it's either an old, hard seal or you've got excessive crankcase pressure. Using it as a retainer is putting a band-aid on a different, potentially bigger problem.

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Agreed, but the problem as I explained was I accidentally blocked the breather during a boost test, thinking it was a vacuum line from the intake side. I don't know about whether or not the seal is worn out, but it does seems pretty hard and well its been in there almost 3 decades so I ordered a new replacement.
 
Agreed, but the problem as I explained was I accidentally blocked the breather during a boost test, thinking it was a vacuum line from the intake side. I don't know about whether or not the seal is worn out, but it does seems pretty hard and well its been in there almost 3 decades so I ordered a new replacement.
Whether you do or don't have a blowby problem you can likely elimate the possibility
Of a seal blowing out by opening the oil cap during a boost leak test.
 
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