2G BS Plug popped out on 15psi BoostLeakTest

[Red 4G63]

Started out working my way up from 5psi to 10psi, fixing leaks as I go and once I got to 15psi, I heard a loud pop. Couldn’t figure out what it was until I started the car and saw oil leaking from the Timing cover. Ripped it all apart to find the plug sitting at the bottom of the cover. Has anyone else had this issue?

I’ve already done a compression test:
Cyl 1-160
Cyl 2-160
Cyl 3-145
Cyl 4-160

This motor supposedly has only 14k on it since it was rebuilt (or so I’m told by a Tuners Moderator that I bought it from). Evo Nitride Crank, eagle rods, arias 8.8:1 pistons HKS 264/264, beehive springs-titanium ret. 3g lifters. That’s all I know about this motor. I also left a comment on the original owners page for some background info on the build. No replies.

I tried a leak down test, but I don’t think I was on the correct stroke per cyl so it was almost always leaking from the exhaust/intake valves. The strange part was, I would also get airl leakage from an adjacent cyl. I’m going to try a leak down test again tomorrow, but I was wondering if anyone else had a similar issue and could get a little more specific as to what their exact issue is/was? All help will actually be appreciated. I’m almost willing to buy people beer to help me!

 

[Red 4G63]

Since I never get responses on forums... let me go ahead and confirm that I generally resolve MY OWN problems.

Leak Down test done properly resulted in finding out that all intake valve stem seals are leaking (I didn't rebuild the motor, and clearly someone was lazy or too cheap to have the valve train looked at), no exhaust valves leak, but all Cyl are technically within 12-18% leak. Still within spec, but something I'll be keeping an eye out for in the near future. So much for only 14k mileage on the rebuild......................

I'll also need to rebuild my MHI 16G center section (owned it for 8years) as I suspect that is why my BS plug popped at 15psi on the boost leak test. I always BL test using the compressor inlet, to ensure I'm capturing all of the intake track and all of the vacuum lines at the same time. Since I had already been through the BL test several times prior to this happening, I didn't have many leaks, thus building access pressure in the wrong places. Hypothesis: I'd be willing to bet the air escaping through the center section (shaft seals) and into the oil pain through the turbo oil drain pipe, built too much pressure in the crank case and caused the BL to blow out. I also cannot comment on how well it was installed, seeing as I didn't install it myself.

Hope this helps someone else down the road.

Cheers.

 

[brian9397gsx]

I'd be more inclined to believe that your pcv is stuck or vent is plugged pressurizing your crank case and that's why you popped out that seal.

 

[Paraquat]

I made a solid aluminum plug for mine, and even then I covered it with RTV.
If I'm not mistaken there's actually a strap clamp kit for the plugs.


--Steve

 

[Red 4G63]

I'd be more inclined to believe that your pcv is stuck or vent is plugged pressurizing your crank case and that's why you popped out that seal.

Hi Brian,
Thanks for responding! The PCV is a concern of mine, since the two brand new ones I bought from Mitsu a few months back were actually rattling (sounded worse than lifter tick - almost like a tattoo gun) and I took the one from the motor I bought and stuck it on. Seems to be working correctly (liquid test/mouth test), but I'll switch it with another to see if that makes a difference.

What do you mean by "Vent"? Which vent are you referring to? I did install a Catch Can (small piece of woven steel at the bottom of can), but I routed that correctly. I will certainly be double-checking that though. VC to "IN" and "OUT" to Intake pipe, correct?

 

[JusMX141]

There will always be boost pressure leaking from the turbo into the crankcase as the dynamic type seals on both sides of the shaft work like a piston ring and do not seal 100%. There are gaps between the seal rings and the groove on both sides and also a gap in the seal ring itself up to .005" which will just bleed pressure directly into the crankcase via the oil drain. That's 100% normal.

If you're attempting to verify there are no leaks in the piping anywhere the best place to accomplish this is install the boost leak tester at the coupler just after the compressor housing...otherwise any turbo is going to fail a boost leak test by nature, even if it's brand new.

 

[Red 4G63]

I made a solid aluminum plug for mine, and even then I covered it with RTV.
If I'm not mistaken there's actually a strap clamp kit for the plugs.


--Steve

Hi Steve,

Thanks for jumping in! I'm using the rubberized OEM Mirage version bought directly from STM with their recommendations of just a little Black RTV around the edge, wipe up the access and let it cure (24hrs). Again, I didn't actually install it, my cousin did (cert. toyota tech), so it's likely he didn't use enough RTV. I can confirm that I've reinstalled it with A LOT more RTV around the outside sealing it up better.

 

[Red 4G63]

There will always be boost pressure leaking from the turbo into the crankcase as the dynamic type seals on both sides of the shaft work like a piston ring and do not seal 100%. If you're attempting to verify there are no leaks in the piping anywhere the best place to accomplish this is install the boost leak tester at the coupler just after the compressor housing...otherwise any turbo is going to fail a boost leak test by nature.

Thank you for confirming my initial belief, I really hate second guessing myself... but when I have very few DSM guru's in my area, it's really hard to get to the bottom of these anomalies. I just keep telling myself "It's a DSM thing...." haha.

The only other thing that makes me concerned is the drip of oil that is always waiting for me on the 16G inlet when I take my FP intake pipe off... would that concern you as far as seals go? Again, I did just install the cheapo Catch Can, so I'm hoping it will at least help a little more than nothing at all! I'm up for any other suggestions you may have though!

 

[JusMX141]

There's oil in the intake piping of almost any daily-driven boosted application. It's the result of plenty of on/off/on throttle situations. The crankcase pressure issue is more than likely the valve seals- it's hard to hurt a MHI turbo.

 

[Red 4G63]

There's oil in the intake piping of almost any daily-driven boosted application. It's the result of plenty of on/off/on throttle situations. The crankcase pressure issue is more than likely the valve seals- it's hard to hurt a MHI turbo.

Well this certainly makes me feel better about the 16G. I'm going to run the car for the rest of this year and hopefully continue with the Remote Tuning I've been doing with TedTech in CA, as long as he's ok with continuing. I sent him the numbers and he seems to thing things are reasonable enough (not good obviously, but not catastrophic). I'll start saving to have the head machined and replace everything over the winter time. It's been over a year since the original motor crankwalked on my and took out the crank sensor, so I'm jones-ing to enjoy my convertible again.

Thank you for your knowledge/expertise!

 

[chrysler kid]

I found the only way I could boost test my system was with a boost source hose, not a compressor inlet.

Valve stem seals are easy to do yourself, just time consuming. It's a timing belt job that just goes a step further removing the cams to remove the valve springs to replace the seals.

Man up son. Unless you think your weekend off is worth more than $1200 that a shop would charge

 

[Red 4G63]

I found the only way I could boost test my system was with a boost source hose, not a compressor inlet.

Valve stem seals are easy to do yourself, just time consuming. It's a timing belt job that just goes a step further removing the cams to remove the valve springs to replace the seals.

Man up son. Unless you think your weekend off is worth more than $1200 that a shop would charge

Touché! My weekend is worth more than that, but I get your point good Sir! The motor swap was beyond my mechanical ability and I managed to figure it out, I’m sure I could handle valve seals, just need some creative tools like Jafro!

What do you mean about “boost source hose”? Is that the same as IC pipe after the turbo?

 

[chrysler kid]

Yeah I had a 3/8 hose I use off of the j pipe.

Valve stem seals use a $50 tool from Amazon or eBay

First rule of dsm ownership, never trust another dsm owner or shop, everyone is trying to cut corners to make money. These cars can not be done in flag hours trying to beat the book. They require spealists

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[007jimmy]

Yeah I had a 3/8 hose I use off of the j pipe.

Valve stem seals use a $50 tool from Amazon or eBay

First rule of dsm ownership, never trust another dsm owner or shop, everyone is trying to cut corners to make money. These cars can not be done in flag hours trying to beat the book. They require spealists

Yes! Certain tools can save so much time. Also are worth the cost and then some on the very first use. Did the whole valve job myself with the Eurosport 4g63 valve install tool and a 10mm socket. I even lapped the valves while I was in there. Just took a few hours of my time (worked slowly as a precaution).
Edit: By no means I am a expert at doing this. It was my first time on my own after doing extensive research on the forums. Come to find out it's easier then I thought. Good luck

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[Red 4G63]

Yeah I had a 3/8 hose I use off of the j pipe.

Valve stem seals use a $50 tool from Amazon or eBay

First rule of dsm ownership, never trust another dsm owner or shop, everyone is trying to cut corners to make money. These cars can not be done in flag hours trying to beat the book. They require spealists

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I will be looking into that tool today! You’re right though, I shouldn’t trust so easily. Thank you for jumping in here, I needed that kick in the “DIY” ass!

 

[Red 4G63]

Yes! Certain tools can save so much time. Also are worth the cost and then some on the very first use. Did the whole valve job myself with the Eurosport 4g63 valve install tool and a 10mm socket. I even lapped the valves while I was in there. Just took a few hours of my time (worked slowly as a precaution).
Edit: By no means I am a expert at doing this. It was my first time on my own after doing extensive research on the forums. Come to find out it's easier then I thought. Good luck

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That sounds awesome man! I’ll see what else I can do while I’m in there to make sure that everything is sealed up and clearance checked. I just bought my TDC Jafro special TDC Gauge and magnetic stand so I’m on the right path!

 

[MichaelSuch]

When putting the BS plug back in I always used the OEM balance shaft plug as found in the link below, and spread some red loctite around the surface that mates with the front case. I've never had any leaks or any of them pop out.

 

[Red 4G63]

When putting the BS plug back in I always used the OEM balance shaft plug as found in the link below, and spread some red loctite around the surface that mates with the front case. I've never had any leaks or any of them pop out.

Thanks for your advice! I already put it back in with some Black RTV (pic below) but... in the event it pops back out, I’ll definitely be using your method. This motor is supposed to hold 20psi all day long, so once I get things dialed in I’ll have to keep an eye on it.

 

[pauleyman]

Thanks for your advice! I already put it back in with some Black RTV (pic below) but... in the event it pops back out, I’ll definitely be using your method. This motor is supposed to hold 20psi all day long, so once I get things dialed in I’ll have to keep an eye on it.

The 20psi you're referring to should have little to do with that plug. Crankcase pressure is entirely a function of intake airflow and how well the ceankvaae is evacuated and how many leaks are present from intake/cylinder sources into the crankcase. The results could be the same for a stock motor or a race motor.

 

[Red 4G63]

The 20psi you're referring to should have little to do with that plug. Crankcase pressure is entirely a function of intake airflow and how well the ceankvaae is evacuated and how many leaks are present from intake/cylinder sources into the crankcase. The results could be the same for a stock motor or a race motor.

So the air leaking past the intake valve stem seals out into the head and then going down the oil passages into the block, am I thinking of this correctly?

 

[pauleyman]

Yes that is correct. But the build of the motor really doesn't have much to do with that. When you said made to handle 20psi that really wasn't relevant. That was my point. The cylinders were made for 20psi. As long as the rings seal well and the stems seal well you're fine. Apparently currently at the moment you are not fine and you're fixing it. I'm more curious about crankcase evacuation actually. I've seen motors that want to blow off the oil cap when you unscrew it at idle. Guess you were blowing dipstick out also unless it was very new or held in place.

 

[Red 4G63]

Yes that is correct. But the build of the motor really doesn't have much to do with that. When you said made to handle 20psi that really wasn't relevant. That was my point. The cylinders were made for 20psi. As long as the rings seal well and the stems seal well you're fine. Apparently currently at the moment you are not fine and you're fixing it. I'm more curious about crankcase evacuation actually. I've seen motors that want to blow off the oil cap when you unscrew it at idle. Guess you were blowing dipstick out also unless it was very new or held in place.

The dipstick is about 6yrs old from STM but it’s a stock version, no spring assist or hold down, it never came out. The oil cap had air leaking out but not enough to make it blow off when unscrewed (that’s also fairly new). Will I be causing damage if I drive the car conservatively the rest of the summer and then do the valve stem seals over the winter?

 

[chrysler kid]

Not sure what you're referring to. Bad valve stem seals will cause the car to smoke pretty severely at idle. So methinks your balance shaft plug popping out was just a coincidence

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[rEclipserGST]

Very curious about your crankcase ventilation setup as well. Please post a picture. Of catchcan/modified setup or factory setup.

 

[Red 4G63]

Very curious about your crankcase ventilation setup as well. Please post a picture. Of catchcan/modified setup or factory setup.

Pics coming shortly.