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Hoffman called today with the good news that my heads passed the pressure test and crack inspection. Valves and guides are in excellent shape. He is machining the faces, installing 5 helicoils in exhaust mounting threads that are buggered up, machining the exhaust mounting faces, ultrasonic cleaning and bead blasting external surfaces, installing new springs and seals. His words, “heads will be like new”. Should be ready in a week.
Meanwhile, I took this good news and went ahead and ordered the new short block from my local dealer. None available in the Atlanta warehouse, so it will be coming from Germany, in about 2 weeks.
So, I have a couple of weeks to clean the intermix out of the coolant tubes and radiators...
Hoffman called today with the good news that my heads passed the pressure test and crack inspection. Valves and guides are in excellent shape. He is machining the faces, installing 5 helicoils in exhaust mounting threads that are buggered up, machining the exhaust mounting faces, ultrasonic cleaning and bead blasting external surfaces, installing new springs and seals. His words, “heads will be like new”. Should be ready in a week.
Meanwhile, I took this good news and went ahead and ordered the new short block from my local dealer. None available in the Atlanta warehouse, so it will be coming from Germany, in about 2 weeks.
So, I have a couple of weeks to clean the intermix out of the coolant tubes and radiators...
That's not "good" news, that's "excellent" news !!! Your bill will be much less than I would have expected !! I love it when that happens....
Last edited by Porschetech3; 03-09-2018 at 03:22 PM.
Look out for hoses that feel oily, depending on how long the intermix sat in there , it can get saturated into the hose rubber , when they get like that they are junk!!
Look out for hoses that feel oily, depending on how long the intermix sat in there , it can get saturated into the hose rubber , when they get like that they are junk!!
Yes, this is good advise. Also run a couple gal of brake clean through as it will adsorb oil and will save any hoses that are just moderately saturated with oil.
Those heads look awesome! I don’t understand why he would use heli-coils if he was doing “weld repairs” of the exhaust bolt holes though... Why not just re-drill and tap them?
Now is a good time to measure and fit SS studs on the exhaust manifold, installed with a little bit of blue locktite. Never have to worry about those exhaust manifold bolts ever again.
Those heads look awesome! I don’t understand why he would use heli-coils if he was doing “weld repairs” of the exhaust bolt holes though... Why not just re-drill and tap them?
Aluminum threaded heads and steel bolts don't play nice. A steel helicoil in the head and you can play stud/bolt removal install different headers etc. and not lose the hole again. Honestly, these probably should've had threaded inserts from the factory given the cost of a Porsche. Removing steel bolts from aluminum heads that have seen that much heat almost always causes threads to break. The very different heat transfer and thermal expansion properties of the two metals destroy the threads.
Len Hoffman told me it was important to use a copper based anti-seize compound for all threads (helicoils or not) in aluminum heads, including spark plug threads.
Aluminum threaded heads and steel bolts don't play nice. A steel helicoil in the head and you can play stud/bolt removal install different headers etc. and not lose the hole again. Honestly, these probably should've had threaded inserts from the factory given the cost of a Porsche. Removing steel bolts from aluminum heads that have seen that much heat almost always causes threads to break. The very different heat transfer and thermal expansion properties of the two metals destroy the threads.
Ahhhhh... now I get it. It's strange, when I did all the work on my engine last year, the exhaust manifold bolts were some of the easiest to remove - and the manifolds/flanges themselves were super rusted/corroded. I replaced the the bolts with new ones and used copper based anti-seize... I'm getting ready to replace the manifolds with some Agency Power headers, so we'll see how well it worked (I've only driven about 2k miles since the engine work so it won't be a problem I'm sure). If I remember correctly, the torque value is not very high on the exhaust manifold bolts (around 30 ft.lbs from memory) - I'd bet that they get get over torqued more often than not.
Copper based anti seize does sound like a good idea. Torque is usually pretty low on exhaust manifolds. The gasket is designed to seal as its crushed at optimal torque. Overtorquing any fastener is a bad idea. It's not a case of a little more will do like seasoning your food. Once fasteners exceed their yield strength it's going to be bad. A lot of modern fastener specs are set so the fastener yields and is never reused.
I'm going to have to remember to get some copper based thread sealer. Anything that can last given the heat will help.
I look forward to following along with the rebuild too!
03-09-2018, 02:59 PM
