944S pressure reducing valve removal

1987944Sick · 11-30-2008, 12:23 PM

so now that i have the head off which took more then a week for me to do..how to i remove the pressure reducing valve from the head? how do i know if it is bad? and how do i know if the lifters are bad?

2Tight · 11-30-2008, 12:56 PM

There are two different methods of removal and re-installation depending on the year of the head. Do a search on 'checking lifters' but if you can dpress them with your finger or thumb they are usually bad and won't stay pumped up. Why would you need to remove the PRV? Are you having the head reworked? They can -resurface the head without removing it.

1987944Sick · 11-30-2008, 01:00 PM

i had this ratting noise..so i am taking things apart to find out what it is...long story..

1987944Sick · 11-30-2008, 01:02 PM

[QUOTE=2Tight;4332012]There are two different methods of removal and re-installation depending on the year of the head. Do a search on 'checking lifters' but if you can dpress them with your finger or thumb they are usually bad and won't stay pumped up. Why would you need to remove the PRV? Are you having the head reworked? They can -resurface the head without removing it.[/QUOTE/] its a 87 944 s 16valve

1987944Sick · 11-30-2008, 01:07 PM

whats one way of removing it

1987944Sick · 11-30-2008, 02:37 PM

i removed it..the set screw was getting in the way of pulling it out...now how do i know if the valve is bad..i checked the lifters and they all bounce back about the same..

Zero10 · 11-30-2008, 04:08 PM

How many threads are you going to start for this issue? I count 10 already

2Tight · 11-30-2008, 04:21 PM

Quote:

Originally Posted by 1987944Sick

i removed it..the set screw was getting in the way of pulling it out...now how do i know if the valve is bad..i checked the lifters and they all bounce back about the same..

I'm not familiar with the 16V head so hopefully you'll get better info. The 8V head is OK for a skim cut without removing the PRV if it is cleaned well. Again if you can depress a 'fully oil charged' lifter with your finger or thumb without a Hulk type thumb, bounce back or not, I would not use it. Have you tried depressing them while they are submerged in oil and then letting them refill while under oil? The lifters should be hard as a rock after that and very difficult to manually depress if they are full of oil. A lifter that won't pump up is useless, will tear up the cam, and make you wish you never bought the car. Some people soak them in kerosene for weeks to free them, others just look for good used ones. The INA lifters Porsche sells as OE have a questionable track record at best.

1987944Sick · 11-30-2008, 06:05 PM

Quote:

Originally Posted by 2Tight

I'm not familiar with the 16V head so hopefully you'll get better info. The 8V head is OK for a skim cut without removing the PRV if it is cleaned well. Again if you can depress a 'fully oil charged' lifter with your finger or thumb without a Hulk type thumb, bounce back or not, I would not use it. Have you tried depressing them while they are submerged in oil and then letting them refill while under oil? The lifters should be hard as a rock after that and very difficult to manually depress if they are full of oil. A lifter that won't pump up is useless, will tear up the cam, and make you wish you never bought the car. Some people soak them in kerosene for weeks to free them, others just look for good used ones. The INA lifters Porsche sells as OE have a questionable track record at best.

since it will take a bit for the oil to go in to the lifter..i tryed it with the kero and i can still push it in with my finger...Do they all go bad at the same time? or just one or few?

2Tight · 11-30-2008, 06:30 PM

Quote:

Originally Posted by 1987944Sick

since it will take a bit for the oil to go in to the lifter..i tryed it with the kero and i can still push it in with my finger...Do they all go bad at the same time? or just one or few?

Again...if you can depress them with your finger when they are full of oil they are worn out. They can all go bad together if proper maintenance was not observed. It could be your PRV was sludged up at some point denying adequate oil pressure and supply to the upper head and cam. You can use the lifters that feel soft but don't complain when the engine is just as noisy as before.

Zero10 · 12-01-2008, 07:28 AM

There is a check valve inside each lifter. If you can depress them by hand that check valve isn't sealing.
Could be from buildup on the mating surfaces inside of the check valve (I say could be, because this is the only option you may be able to fix at home). Sometimes kerosene or ATF will free them up, but it sounds like they aren't sealing up for you, and if after repeated squishing in kerosene or ATF they still aren't sealing up then the soft ones need to be replaced. You don't need to replace all of the lifters unless you are paranoid. Typically every 944 will have a couple go soft over their lifetime, and the new ones have a worse track record than the old for various reasons.

To make sure the old ones are bad, put the soft lifters in a solvent (such as kerosene or ATF) and squish the button a number of times (like 20-30 presses), if it still doesn't firm up then leave them to sit for a day or two and repeat. If after a couple of tries like this they are still soft then they are done for (unless somebody else has a miracle method here. Personally I'd like to try an ultrasonic cleaner on them but I don't have one).

Sounds like you have finally gotten down to the issue

1987944Sick · 12-01-2008, 12:08 PM

alright...they all go in out at least a bit,few seem harder but they all go in...ONE more thing i noticed today,when i shake them most of them make noise,something is hitting something inside,that could be why it was making the noise?...and i can spin the little thing inside with my hand..

2Tight · 12-01-2008, 03:43 PM

Here's a pic if that helps you understand what's inside