Jason_86_951

Hey Andrew,
I'll be in Taipei next month I'd love to see your 3L conversion!

MachSchnell

I have to say, I agree with Jon, with as much as this happens I can't believe it's not something more simple and common than combustion gasses passing into the coolant...I'm sure that may be a problem on occasion, but shoot, how the heck could this many cars have cracked blocks or heads and have it not be something talked about...nobody thus far has stepped up and said that they had the same problem and had a cracked head...all of us talking about this now have just replaced head gaskets. I suppose perhaps replacing the rad is possibly in my future too. When it occurs, I can't say other than that I only occasionally notice it after I shut teh car off and walk away, but it usually happens within the next 5 minutes, so the pump seems to have something to do with it...

Anybody ever have success finding a higher pressure rad cap?

BTW - usually running 15psi but I'll be going 18 soon.

Songzzz

Btw, my combustion chamber leak was because of the confusion between lbs.ft and Nm. Raceware says 65 lbs.ft and if you do 65Nm, that is only equivalent to 47.94 lbs.ft, hence leak occured.

Jason, sent me a PM, we'll meet up.

cheetah chrome

what about a crack in the turbo housing allowing pressure to get into the water passage once the turbo is up to temp and under pressure? i read all of the posts but you never mention the condition of the turbo.

Jon Schepps

Songzzz,

Yes, its not caused by the turbo boiling water, as I was originally hoping.

Where did get that tightening procedure for the Raceware studs? According to my Raceware installation instructions, it says tighten to 30, then 50, then 65 ft/lbs. Nothing about waiting in between steps. And the final spec is 65 not 80! Huh?

If its supposed be 80 and I've been using 65, that would explain things.

BTW, I've put on 2 head gaskets within 2 weeks. This symptom appears immediately, so its not like the gasket is getting burned up. The one I took off 2 weeks ago looked fine (it was a Cometic MLS gasket). A WFR is on there now.

Jon.

Songzzz

Jon, yes Raceware says 65 ft.lbs.

I didn't follow instructions and torque down to 80ft.lbs instead, no more leaks.

Waiting between steps is just a safety precaution. You are clamping down new gaskets so I guess it is better to allow some time for it settle in. This should eliminate the hassle of re-torque.

nickhance

I'm running 18psi.

dand86951

Jon, one question is whether or not your engine has original cylinders, ie aluminum or has it been sleeved?

Jon Schepps

dand86951- original cylinders (and pistons and rings), and they're smooth as glass.

nick- did the start of the overflowing coincide with raising your boost to 18psi?

jason_86-951- not likely the oil to the turbo is blocked, as that would cause the unit to fry in no time due to lack of lubrication.
Plus, my oil temperature sender is tapped into the large banjo bolt on the turbo oil return line to the pan, and its certainly reading hot oil.


Songzzz- 80 ft-lb on the Racewares? Seems scary to me. Also is a bit like treating the symptoms instead of fixing the cause.
But are you saying that you had this same overflow problem, and it went away when you tightened up the head?
What boost level are you running?
Then maybe O-ringing the head is another "fix".

Jon.

nickhance

Jon:

Unfortunately I can't say. What I can say is that I believe I've had this problem since even before I replaced the headgasket (when I was running lower boost as well). However, the system was allowing coolant to escape at the water pipe near the top of the engine (the one with the bleeder valve) and dumping it on top of the block. I replaced the hose attached there when I rebuilt the top end and it started to push it out of the expansion tank.

Jon Schepps

Sounds like the problem existed before and after your top-end rebuild. It just leaked from the weakest link, which was a bad hose at the top of the block before you replaced it, and then the pressure relief of the exp tank cap after you replace it.

Perry 951

Jon - Yea, I did several tests and several runs while using the test strips. I replaced my head gasket after 2200 miles on a 100% fresh motor because of some oil/water contaminaton. Once the gasket was replaced, my oil and water stay in their respective passages, but I'll still send about 6oz of coolant into the abyss.

It's strange in the fact that I can top off my resivoir each day, drive just far enough to heat cycle the motor twice, then pop the hood to see that 4-6oz of coolant is gone. If I leave the coolant level alone (low), it will stay at that level regardless of how far, or hard I drive it.

Example - 840 miles from ATL to NJ.. topped off before we left, and also topped it off at every 1/2 tank we stopped. Every top off required 10-12oz. (80% of the trip was at night in temps below 70.)
Example 2 - 840 miles home, 6-8oz low when we left, 8oz to top it off when I got home. (80% of the trip was in temps above 80.)

MachSchnell

So Perry, if you leave it low, it never gets lower? Why top it off then if you don't mind me asking? Why not just figure that the low level is the proper level and leave it be? (I don't ask to be snide, I'm actually wondering about the same thing myself, because I top it to be safe, but have been thinking "would I hurt anything by not topping it off")

Jon Schepps

Assuming the coolant is going out the overflow, then your exp tank pressure is exceeding the cap pressure. These cars are supposed to use a 1.5 bar cap, or about 23 psi. That's pretty high compared to most cars, and for normal driving around you should definately not exceed it.
I think what's happening is that you are pressurizing the coolant, but with the level down low, the pressure vents without blowing out coolant. If the level is above some critical point, then you blow out that coolant.

So, are you pressuring the tank? One way to tell is to check the firmness of the fat hose coming off the water pump (going to the rad). If you press on it when the car is warmed up (idling), it will feel squishy, and you'll see the coolant in the tank slosh up and down. Then drive the car hard for bit, and then check that hose. Is it hard? That would indicate a lot pressure in the exp. tank.

Jon.

StoneGrey

Jon - you said
"Just for kicks, I just used a cooling system tester to pressurize the coolant to 22 psi. Caused a leak to occur somewhere in the radiator. Doesn't seem to be hose, but I can't see where its coming from."

As you know, the Rad is metal and the sides are plastic, I had a leak coming from this interface on the drivers side, it's a typical point of failure for water cooled Porsches. Maybe it's time you go to air cooled Porsches like your buddies Dan and Pete!

Cheers,
StoneGrey