1998 Boxster Suspected Head Crack (or gasket)

[alex1982]

Hi All

I suspect my 98 Boxster 2.5 has a cracked head or blown gasket but was hoping you could confirm (or suggest otherwise!!!! ) based on my symptoms:

-Occasional white smoke on cold start (quite a bit)

-Expansion tank appears to be under a lot of pressure (cap hissing, even the new xxx04 one)

 

-As soon as I rev above 3K, expansion tank pressurises big time, coolant level lowers and low level light flashes.

When I stop the car to (carefully) release pressure at the cap, white exhaust fumes come out of tank (smells of gasoline) and coolant level raises back again.

 

To me the instant compressing at high revs is the giveaway as the warning light follows within seconds, and it appears to fill the cooling system with a pocket of fumes.

 

The crack however must be small because everything is normal if I keep the revs below 3K, even after a 30min drive.

The tank does seem under a lot of pressure though, and the manual bleeder valve will sometimes stay up after several days until I remove the cap to release the pressure...

 

I tried burping the car multiple times, and replaced the cap with the 04" version.

 

Could the above point to anything else?

Thanks

Alex

[JFP in PA]

4 hours ago, alex1982 said:

Hi All

I suspect my 98 Boxster 2.5 has a cracked head or blown gasket but was hoping you could confirm (or suggest otherwise!!!! ) based on my symptoms:

-Occasional white smoke on cold start (quite a bit)

-Expansion tank appears to be under a lot of pressure (cap hissing, even the new xxx04 one)

 

-As soon as I rev above 3K, expansion tank pressurises big time, coolant level lowers and low level light flashes.

When I stop the car to (carefully) release pressure at the cap, white exhaust fumes come out of tank (smells of gasoline) and coolant level raises back again.

 

To me the instant compressing at high revs is the giveaway as the warning light follows within seconds, and it appears to fill the cooling system with a pocket of fumes.

 

The crack however must be small because everything is normal if I keep the revs below 3K, even after a 30min drive.

The tank does seem under a lot of pressure though, and the manual bleeder valve will sometimes stay up after several days until I remove the cap to release the pressure...

 

I tried burping the car multiple times, and replaced the cap with the 04" version.

 

Could the above point to anything else?

Thanks

Alex

Welcome to RennTech

 

These engines use multi layer steel head gaskets that are actually stronger than the head or block castings; literally, they never fail.  I would suggest having your cooling system pressure tested, you may have a failing or slipped cylinder liner.

[alex1982]

Thanks for your quick welcoming answer JFP!

Ouch! I'll try to get it pressure tested then.

Thanks

Alex

Edited September 27, 2019 by alex1982

[JFP in PA]

1 minute ago, alex1982 said:

Thanks for your quick welcoming answer JFP!

Ouch! is there a way to confirm a slipped cylinder liner without removing the engine? 

Thanks

Alex

 

Run the cooling system pressure test; if it doesn't hold pressure, run cylinder by cylinder leak down tests to identify which hole(s) it is.

[Geir Nordvik]

It sounds like the oil/air separator needs to be replaced.