[MLB]

I replaced Vario cam chain and pads last fall, and that's in another thread. after retiming the cams the butt-o-meter noticed a significant improvement in power. Definitely in for a valve job. But what about resurfacing the head? Is that something you can only decide after taking it out and checking it?

Partial Post: Please Login or Register to read the full post.

[vliegwielolaf1234]

Yep , that is only possible to check  with the head removed , all depends , if surface is not corroded or warped , you might not even have to do anything , exept the valve job .

Partial Post: Please Login or Register to read the full post.

[JWahlsten]

Michael,

 

When you have the head in for the valve job, have them check the flatness of the mating surface.  Mine didn't need to be decked.  I cleaned the top of the block with fine pads on a metal block, so I didn't introduce any scratches that would inhibit sealing.  So far so good.  Two track days down, no coolant leakage, and improved power on the top end

 

When you're putting it back together, it's a great time to do motor mounts and hoses...

 

While you're in there...

 

Joel

Partial Post: Please Login or Register to read the full post.

[MLB]

Thanks Joel, yep i replaced OEM motor mounts and OPG, and lower rad hose last year. Other hoses on the current list.

But my local indie porsche mechanic (a very knowledgable, diligent, thorough and great guy, etc) still insists i havent got a test result that indicates a HG problem: "The fact that it is 22 years old has nothing to do with it, you need some test results that show there is something wrong with it. There are 928s and 944s that are 10 to 15 years older than your car and they still have their original gaskets"

Not that i need to convince him of anything, i will be doing my own work, but he's just trying to provide sound guidance, knowing that i am also participating on this forum (of which he will be forever skeptical. :0)

Partial Post: Please Login or Register to read the full post.

[flash]

it makes me crazy when i hear anecdotal things that mislead people into a false sense of security.  just because there are cars that have not yet failed, it does not mean that the problem does not exist.

 

the head gasket used in our car deteriorates over time.  there are pics here floating around of exactly that.  it's not pretty.  how fast it happens depends on a lot of things, not the least of which is regular flushing of the cooling system, which almost nobody does.

 

when you did the leakdown, did you do it one plug at a time, leaving the plugs in the other 3 holes?

Partial Post: Please Login or Register to read the full post.

[MLB]

Flash, the leakdown tool (admittedly cheapo harbor freight) instructions said to remove all plugs, so i had them all out and just advanced to combustion stroke TDC for each cylinder in succession. Very slight hissing was apparent for each cylinder, that seemed to come from where the intake valves are, but cyl 1 in particular had a hiss from the oil dipstick tube and AOS/fill. Cyl 2 also had slight hiss thru intake, audible at MAF.

Partial Post: Please Login or Register to read the full post.

[kwikt]

I had 160,000 on mine when I pulled the head. Head gasket was leaking for a while and defiantly needed to be resurfaced.

Partial Post: Please Login or Register to read the full post.

[MLB]

Kwikt, when u say leaking, what symptoms /problems did u notice that led to repair and replace?

Partial Post: Please Login or Register to read the full post.

[kwikt]

Always adding a little coolant.....always. With no visible leaks.

Partial Post: Please Login or Register to read the full post.

[MLB]

I found out the coolant test for exhaust gases i just a pH test. I have pH strips at home so i checked new 50:50 coolant against what was in the reservoir; same pH, about 6.5. I dont know how much of a pH difference to expect, but in any case i still dont have a conclusive test result. Next i want to check again that both fans are actually still working when warmed up, but ive never seen the coolant gauge rise above normal, except for sitting in the autocross queue on a hot summer day.

Partial Post: Please Login or Register to read the full post.

[MLB]

I pulled the head last nite. Well...that is to say i disconnected everything. But the leverage angle is terrible, and with those thin fenders right there, i just wasnt strong enough to grunt lift it out! Have to try again tonite, think of a smarter way. :0)

Partial Post: Please Login or Register to read the full post.

[williamoss]

_{OK my question is regarding the replacement of the upper and lower pads by a mechanic. I do not want to pay for labor twice.}

 

_{Since as I understand it one has to remove the two cam shafts in order to replace the lower timing shaft pad, is this a good time to replace the head gasket? And also the timing chain? my car is a 1995, with 93,000 on it. And should one automatically do a valve job at the same time? Are there any other parts that should be changed at this time?}

Partial Post: Please Login or Register to read the full post.

[Bulti]

The cam shafts have to come out, together with the chain, so have that replaced also. When the cams are out, you are halfway there to change the head gasket, so if you got an extra buck on the side this may be a good idea. And when the head is removed might as well have the valves done. Also a good opportunity to replace or clean any ticking valve tappets!

Partial Post: Please Login or Register to read the full post.

[chuaed]

Hey guys - I am having a similar issue with coolant spewing out from the overflow tube when parked after a 15min drive. Had to refill it with approx 1L of water/coolant to get it back to just below the MAX level. Gonna go with the easy fix of changing the expansion tank cap first. Any idea what would be the recommended pressure rating for the cap? My current one indicates 140, which presumably means 140kpa. Wondering if it would be advisable to get a 150kpa replacement and hopefully keep a higher pressure. Maybe that will keep the coolant from overflowing?

Partial Post: Please Login or Register to read the full post.

[MLB]

Hi chuaed,

I'm using the 150 cap (150 kPa, 1.5 bar, 21.75 psi)

But over the winter when I removed and flushed the radiator a big piece of the formerly missing-in-action thermostat rubber gasket fell out of the bottom hole where the blue plastic plug goes. I wonder if that was clogging up the flow path and contributing to my overflow when I would stop or shut off the car.


I wanted to add that the overflow didn't happen every time I drove the car, but when it did it was significant volume of at least 100 mL.

Partial Post: Please Login or Register to read the full post.

[chuaed]

MLB - I had the same experience previously for a period of time, would find a puddle of coolant on the garage floor intermittently but it was finally resolved (see my older post above) until it happened again two days ago. Plan to get a new cap to see if it helps.


Is yours still an issue?

Partial Post: Please Login or Register to read the full post.

[MLB]

I wish i knew!

The car hasn't run long enough to warm up in six months. (see my supercharger # 60 thread)

Hopefully get everything resolved by the end of yet another week gone by

:0/

Partial Post: Please Login or Register to read the full post.