Porsche Enthusiasts Club Forum

pauly.can you enlarge on that? whats hydraulic lock and how can you avoid it?

Water does not compress as readily as air/fuel so if you have too much water inside one of your cylinders and you run the engine you will get big problems. Basically the piston cannot compress the water so something metal has to break - cylinder, piston, head etc

As Paul said, water collects in a cylinder, you start the engine, it fires on other cylinders, and if the cylinder with the water has the valves closed it can cause damage. To be on the safe side pull the plugs and spin it over before you drive it to be repaired.

Oh no just read your thread. Hope you get it sorted soon mate.

Thanks for that information you two.Ive been putting a small amount of water in the header tank for some time now(roughly 1/2 pint every 300 miles or so) .Done a compression test and the results were ok .Ive looked all over with a torch and cant find any obvious leaks,theres nothing on the floor either running or not,so I cant for the life of me find out where the water is going.The engine is running fine,no misfires.I did suspect the water pump but it looks ok from the outside,maybe I should do the compression test again.Hope the water is not collecting in one of the cylinders like you say.Regards John.

Any water mixing with oil e.g. on the dip or oil filler neck?

The symptoms can be more subtle than that. Does it run a bit lumpy when cold & improve as it warms up or the other way around? Do you get lots of white smoke all the time when it running? Do a plug check, is one plug very different to the others? Whilst cold take the heade tank cap off & start it, as it warms is there a stream of bubbles in the header tank?
I''ve done countless head gaskets very few have done the traditional symptoms, water in the oil & vice versa. The best was the Lancia Beta a few years ago you could start it up, it'd run fine then as the thermostat opened it vesuvioused it's header tank all over the engine bay You certainly didn't stand close to it

Agree it's usually the last sign (water and oil excessively mixing), but thought it worth mentioning. I have also read that on the 944 this can point to a problem with the oil cooler mind..

My Omega DID have the usual signs (eventually), but the rover gave no sign except just overheated one day and the header tank was empty with no obvious mixing of water and oil.

This sounds like excessive water consumption, so unless the leak is external it MUST be head gasket failure.

Sorry you are going through this but it's not the end of the world. Try to look at it as an opportunity to asses the condition of the engine

I've had engines where you get a hose or similar with a pinhole & the leak is only under stress & the water quantity is so small that it vaporises off, so leaving no trace. Result water loss but no obvious signs! Heater matrix can be prone to these faults.
I used to have a radiator pressure tester which was great for finding these sorts of problems.

Quick test for head gasket is to find a garage with a block tester which detects combustion gasses in the header tank.

Yep those minute leaks can be a downright PITA to trace. Apparently newer pork has a tendency to evap from the header cap !

Sniff test is not always conclusive either. The rover passed that one even though I knew the gasket was going. Guess it comes down to test sensitivity / parameters.

hi John,

As Jim said carfully check the plugs visually ...my no 4 plug was "steam cleaned" along with the rh of the combustion chamber....do have access to a borescope ? where are you in the country ? if you are near Wellingborugh or Beds area i ca help

cheers?

Thanks for your help guys!Theres no sign of water on the dipstick,it runs fine when cold and warm,in fact its running really well,theres only white smoke on starting from cold which soon disappears.I didnt know about the bubble test on header tank,will try that later today.I did have a misfire earlier in the year but traced it to a duff coil.I put a new set of leads on which didnt make any difference,then the new coil which sorted it,then I put some new plugs in just to complete the job and its run beautifully since,thinking back ,all the plugs looked the same when I took them out.I thought it could be a pinhole in a hose somewhere hence checking with the torch but if it is I havent found it yet.Thanks Derrick but Im in Doncaster.Whatever it is I think the answer has to be a top end rebiuld.The belts are due to be changed again around Christmas and the water pump too so might as well have the head off at the same time.It hasnt got any worse over the last six months,in fact after some trips i.e.vscc Donington,about 150 mile round trip,I didnt put any water in.Anyway its close to 155000 miles now and I bought it with no service history so I think the old girl probably deserves a rebiuld .Will let you know if I find anything,thanks again.Regards John.

A compression test will give you an idea whether a top-end rebuild is worth doing.

Theres a guy on ebay selling recond' heads for the 8v for £60 out right. Nearly bought one. Depends if you need new valves or not. The other possible big expense is the hydraulic lifters. They are big money & if they are worn then replacement is the only option. When these start to die you loose valve lift & duration & they can cost a lot of horse power. No point buying genuine Porsche as they don't make them anymore. Good luck

Lots of fun and agony but this is where i'm at...will post some more detail's and issues !!lots ...timing belt crank pulley seized solid to crank 1hr to get it off





cheers now to sleep