Well, I just joined the 'I popped a Core Plug' Club...

[Guest 280ZForce]

I'm having the same problem as Garrett. Except this was my 1st time popping a cherry, oops I mean core plug...ssshhhh! The block is red and the plug is circlular, so a cherry resemblance. LOL...anyway, like Garrett, I also haven't had any cooling issues either.

 

So a couple of hours ago I was leaving school after the car was fully warmed up from sitting at idle...left the parking lot in 1st gear and hit 8-10 psi (had boost controller off, so only w/g pressure) before shifting to 2nd. Right as I shifted I noticed a very small amount of white smoke come out from the driver side hood vent.

 

I figured it was exhaust gases from my dump tube that comes off the waste gate that is vented to the atmosphere and just dumps straight down for now.

 

So I'm driving on the freeway...mind you, it is around 10:15pm and around 55-60* outside. I notice the temp gauge start coming up slightly and I find that odd. So I watch it closely as I drive home (around 15 miles).

 

As I'm within 4 miles from my house on the freeway still doing 70 mph, the gauge hits 220*. I come to my exit and as I come to the light, I start seeing smoke come out the hood vent again, so I made my right hand turn and immediately shut it down and coasted into a closed Sam's Club gas station area and white smoke is pouring from both vents now.

 

I pop the hood to make sure there is no fire and to let out all the smoke, I see some coolant around about on the driver side, but no lighting doesn't help that much. Damn, I used to carry my mag light in my car all the time, guess I will start doing that again.

 

I'm 1.5 miles from home and have to call a tow truck because I don't want to risk anything else. So I call AAA and they bring out the flat bed 20 min later and the tow guy was nice enough to unload my car into my garage for me.

 

Pop the hood...get a nice light going and then I notice a hole in the block. Hmmm something is missing...a f*cking core plug...damnit!

 

So where can I get these core plugs and what size?

 

I'm gonna use some of the advice I read from Garrett's post, but I need to know where I can get them.

 

Which method is better the JB weld it in, the 3 bolts to hold it down or the strap across the core plug to hold it down? But wouldn't the methods of tapping for bolts weaken the block strength and make it prone to cracking?

 

Should I replace or check other things to make sure it didn't destroy them from the heat? Like the radiator, the radiator hoses, the water pump, etc?? The radiator and radiator hoses appear to be fine though.

 

 

[Garrett76Zt]

yeah, you popped it on the bad side too, gotta take the manifolds off so you can whack a new one in with a hammer.

 

I've heard numerous people now tell me not to use silicone to put them in. If i was doing it again, I think I'd put them in dry and then JB weld over them, around the rim. If you go that route, go ahead and throw some JB weld over the others as well. I've not had any more problems and I been beating the crap outta the car.

[240hoke]

They are 35mm I believe. I use a shalacking (sp?) Compound when I put freeze plugs in. Sand the block to the clean the rust and stuff off, clean it with acetone, coat both the block and plug with shalack and let it dry then hammer the new plug in. Its kinda like contact cement and does a good job of sealign the hole well. Ive been running 15-20 on my l28 for almost 3 years now and never blown a freeze plug I dont think that has anythign to do with it, or at least it shouldnt.

 

The last motor i took apart with blown plugs had a blown headgasket and warped head from over heating

[cygnusx1]

Could it be caused by the block flexing? I doubt it but you never know.

[badjuju]

Wouldn't JB welding it in render a freeze plug semi-useless? I thought the purpose of a freeze plug was to allow them to pop out instead of the block cracking if all the coolantwater in your system freezes?

[cygnusx1]

The freeze thing is pretty much a myth. They are mainly "core plugs".

 

http://en.wikipedia.org/wiki/Freeze_plug

[JMortensen]

I always use Permatex Aviation on the freeze plugs.

 

As to the cause, I think 510six nailed it on the other thread:

I vote for the combustion pressure getting into the coolant passages.When I ran the big shot of N20 I always have had the coolant catch can fill up.Once the block was O ringed and a NISMO HG was used the problem wasn`t as bad but it still happens.

[mom'sZ]

Wouldn't JB welding it in render a freeze plug semi-useless? I thought the purpose of a freeze plug was to allow them to pop out instead of the block cracking if all the coolantwater in your system freezes?

If Paul (BRAAP) sees this we're going to get another lecture

(kidding Paul)

[dr_hunt]

Is this really a widespread problem with the turbo L6's?

[cygnusx1]

I find it hard to believe that combustion pressure would blow out freeze plugs before blowing up a radiaor hose or the radiator cap. I guess it's possible.

 

Doc, I had never heard of it before until these guys brought it up.

[BRAAP]

Wouldn't JB welding it in render a freeze plug semi-useless? I thought the purpose of a freeze plug was to allow them to pop out instead of the block cracking if all the coolantwater in your system freezes?

 

If Paul (BRAAP) sees this we're going to get another lecture

(kidding Paul)

 

 

 

Too late, I already read it and as you may have guessed, I about came out of my skin…

 

 

NO NO NO!!!!!! They are NOT FREEZE PLUGS!!! They are CORE plugs…

 

Engine builders/machinist prefer to call those “core plugs” or “soft plugs”, the term “freeze plugs” is a misnomer. Those plugs have absolutely “NOTHING” to do with protecting the block from cracking, and I repeat, “NOTHING” to do with protecting the block from cracking due to the coolant/water freezing etc. those holes in the block are there to allow the sand to be removed when the block was originally cast, i.e. “core holes” so the plugs that fill those holes are called “core plugs”. Back in the early years of the automobile, if a block froze with the old style core plugs, those plugs would sometimes pop out, so most people started to believe that was what those plugs were for, to relieve the pressure of the expanding ice. They were dead wrong. Their blocks and heads still broke and cracked if they froze even though the Core plugs popped out, (I’m sure many of you have experienced this on your own), but somehow, that term “freeze plug” stuck around.

 

 

 

Now, punishment for not reading my post in Garrets thread about popping “CORE” plugs”, I want you to come to the board and write “core plug” 250 times…..

LOL

 

 

Ok, Ill get down off my sop box now…

[BRAAP]

I find it hard to believe that combustion pressure would blow out freeze plugs before blowing up a radiaor hose or the radiator cap. I guess it's possible.

 

Doc, I had never heard of it before until these guys brought it up.

 

The Thermostat is a restriction to flow within the cooling system on the outlet side of the block, (especially when the engine is cold and the thermostat is mostly closed, if not completely closed), and with the water pump pumping water “into” the block, that is a restriction on the inlet side of the block. SO, if the head gasket was to release a small bit of combustion pressure to the cooling system, (i.e. into the block itself), Technically, that high pressure could very well be contained within the block itself due to the restriction that the thermostat and water pump present, (especially when the engine is cold and the thermostat is mostly closed), and there fore pop out “core” plugs, and not blow off radiator hoses, etc.

[RTz]

NO NO NO!!!!!! They are NOT FREEZE PLUGS!!! They are CORE plugs…

 

The core plug Nazi has spoken! :biggrin:

 

From the previous thread (Garrett's), I always felt there was a missing link. The thermostat makes sense to me. The combination of a closed, or mostly closed, thermostat with a leaking head gasket, would seem the right 'recipe'.

[cygnusx1]

Try using compressible coolant instead of that ol' fashioned incompressible stuff.

[Guest 280ZForce]

well i bought a couple of brass plugs (1 extra in case in happens again), some steel wool, permaflex form a gasket sealant 1a & jb weld.

 

I was told to use the brass plugs because steel can corrode and rust a lot easier, as well as it seems that things like to stick to steel more so than brass.

 

2 Questions:

1. So when I use the scotch brite to grind off the surface rust/debris/old sealant of the plug hole, how do I keep the debris from going into the block?

 

2. And to install the plug, I apply the sealant to the plug and the block, then insert plug into the plug hole and use a rubber mallet to hammer it in?

 

thanks in advance guys.

[EMWHYR0HEN]

Wouldn't JB welding it in render a freeze plug semi-useless? I thought the purpose of a freeze plug was to allow them to pop out instead of the block cracking if all the coolantwater in your system freezes?

 

 

Well the freezing point of a 60% ethylene glycol (coolant/antifreeze) is around -60 dergrees F.

 

I think its very unlikely that the plug is there to pop out if it freezes.

[BRAAP]

In Garretts thread, I gave a little advice on core plugs. I only touched the surface last time, this time, lets get a little deeper into the meat of what is going on and why, and as an added bonus, I’ll show how to properly install core plugs!

 

I’m sure my opinion posted here will conjure criticism, and as I’ve posted before, if I’m wrong in what I post, I encourage those in the know to make it known so that others won’t be misguided by misinformation posted by myself, or anyone else for that matter.

 

 

First off, if your core plugs are popping out in a ”boosted” application, especially if they only pop out at “other than race” conditions, i.e. engine isn’t warmed up fully yet, etc. my honest opinion is that your head gasket is releasing combustion pressure, for one reason or another, into the block while the thermostat is mostly closed if not fully closed, and that is why you are blowing out core plugs instead of popping radiator hoses, radiator caps etc. Case in point…. This core plug ”pop out issue” doesn’t seem to happen when at the drags, or under heavy use conditions such as on the freeway or running down the strip at full boost, i.e. your thermostat is most likely open as the engine is fully warm. In the case of 280Zforce, he just left the school parking lot, i.e. his engine was ”cold” and his thermostat was most likely mostly closed, if not fully closed.

 

As a fix, there has been reference in the past to shooting screws through the core plugs themselves and/or covering the core plugs with straps, etc to keep them in place. I ask is that really smart? Do you see where I’m going with this? It is in my best opinion that if you screw your core plugs to the block or cover them with straps, you are doing nothing more than adding a band aid to a broken arm. Sure, it stops the bleeding, but it doesn’t FIX the REAL problem at hand. I don’t think it could be “block flex”. If the block was flexing enough to allow core plugs to release, then the crankshaft would’ve seized up in the main bearings way sooner as it wont tolerate THAT much block flex. If your engine is popping out core plugs, there is DEFINITELY something causing this to happen. I personally feel that it could be at least mild if not moderate detonation ”lifting” the head off the block due to excess cylinder pressures, i.e detonation. The L-series has been documented on this forum with detonation issues to some level or another, even N/A. At any rate, “whatever” issue that needs addressing that is causing the core plugs to “pop out”, first needs to be dealt with.

 

After the ”issue” is dealt with, then lets install your core plugs properly without having to WELD them in. If you don’t address WHAT is causing your core plugs to pop out in the first place, screwing them, epoxy-ing them, strapping them, etc, will do nothing more than show you the next weakest link in your engine at some point in the future. That could very well be the pistons, head, block, rods, etc. Think of the core plugs popping out as your ”little red flag” waiving, telling you that you have some other big issue that needs your immediate attention such as “detonation”, blown head gasket, etc.

 

 

Ok, now on to properly installing core plugs in your L-series block, even full blown hard care high boost applications. If they “poop” out after this, then you have other issues such as detonation to some degree, that needs dealing with.

 

I truly believe that you should leave your core plugs installed withOUT screws or straps because when they pop out they are screaming at you that you have other issues that need to be addressed or it can/will cost you MUCH more next time this issue rears its ugly head, ie. broken engine, instead of popped out core plugs….

 

 

 

 

When you install your new core plugs, be sure that the core plug hole is cleaned. I use a sanding wrap on my die grinder for EVERY engine build that Rusch Motorsports does. I then apply a liberal coat of “Permatex part 1A form-a-gasket” to the core plug hole in the block AND around the perimeter of the core plug itself. I then tap in the core plug in with a socket that fits the core plug nicely. What I mean by “nicely” is the socket fits loosely, not snuggly. You don’t want the “core plug” to collapse around the socket and capture it as you drive it in. Tap in the edge of the core plug is just below the chamfer in the block, wipe off any excess sealant, let stand for at least 24 hours before adding coolant/water. I also agree in not using Silicone as the sealant as it doesn’t really offer any “holding” power.

 

For those who want a little more holding power for “whatever” reason, JB weld can be substituted in place of the “Permatex part 1A”. Just remember that when you rebuild this engine in the future, you should “tip” your machinist/engine builder generously for having to deal with those JB welded core plugs…As an aside, machine shops have been known to fire customers for various reasons….

 

First picture shows a core plug hole with the core plug just removed from Rons F-54 block…

Second picture shows that same core plug hole after being dressed with a sanding wrap.

 

Third picture shows that same core plug hole and the “as packaged” Permatex Part 1A” that we use.

 

 

 

 

 

Hope this helps….

 

Paul Ruschman

[Guest 280ZForce]

Thanks Paul, huge help and will take your advice and install tips. Greatly appreciate your input here.

 

By the way though, my car was fully warmed up. I never drive it until it is, I always start her up and let her idle until she is fully warm and good to go. That's just my precaution to make sure I can drive my car and boost away if needed from the get go.

[Garrett76Zt]

Paul your theory certainly sounds feasible, however I've had this happen with both a stock gasket and a 2mm Metal headgasket (retorqued several times).

 

Also, every time its happened to me the car has been fully warmed up.

 

The only thing that I can really say is common in everytime is that I was doing a burnout (3 times) or accelerating in a low gear (once) AKA very rapid increase in revs. Dunno if thats helpful in figuring it out or not.

 

I will say this, I've not seen any other evidence of headgasket leaking other than that I see small specs of a copper color floating on top of my coolant when I open the cap. Only thing I can think of is that I used liberal amounts of copper spray on my Metal HG when I installed it.

[mom'sZ]

The core plug Nazi has spoken!

told ya

well i bought a couple of brass plugs

I've always heard the brass plugs are for marine applications where salt water will be running through the block. Brass is softer then steel and they will pop out easier. Most marine applications, the motor runs at lower RPMs and at a steady state for long periods. I'd get steel.

The only other thing I can contribute to this discussion is that in my prior experience 'core plugs' always seemed tighter. It's been a while since I've changed one in anything other then an L-28, but it seemed to me the 35mm one in these engines kind of fit... a little loose (doesn't seem to take as much beating to get them in) I'm wondering if a flapper wheel or whatever is actually enlarging the hole slightly, making it easier to pop out. I always just take some emery cloth by hand and just until they are clean. How did you guys do your's (garrett and 280zforce)? Are the ones that popped out ones you guys installed? I'm not completely convinced cylinder pressure is doing it. Guess if one of these guys blows a head gasket or does a tear down and sees evidence of a leak is the only way we'll know for sure.

I agree with Paul that if you strap them in, you may just find the next weakest link. They better all be strapped in. oh well just my two cents, I'll crawl back in my hole now.