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youd probabley get away with a surface scuffing/grind without redoing the hardening (or at least having a surface hardness test done) if you dont push it hard and stay on top of the cooling system...
personally Ive seen too many things that are ment to be hardened to a standard machined and not redone fail. Imho if your going to rebuild something do it all properly and to spec.
I concur. I have pulled heaps of them and ALL of them leave witness marks where the gasket has cut into the alloy surface. I wouldn't / don't risk refitting without a clean up of the head surface. It takes a fair bit to get through the hardened layer, at least 8 to 10 thou AFAIR. By then the head is a throwaway anyhow In my books...Quote:
Originally Posted by Psimpson7
JC
And a little food for thought
The head bolts ... are they the use once only "Stretch bolts" ?? ... Did you use the original head bolts, or install new ones?
Mike
;)
ALWAYS replace the Td5 head bolts. They are a torque to yield type, and are not reusable. Unlike the Tdi ones which although are also torque to yield,they can be re used as long as the engine hasn't been overheated, as the chances of them being stretched are increased. Head bolts are now cheap enough not to cut corners. Just put a new set in.Quote:
Originally Posted by mike 90 RR
JC
Hi all,
I was speaking to a diesel expert in Adelaide and he thinks the problem may be a cracked head. I had the head pressure tested when it was faced and it checked out ok but the diesel bloke seemed to think that some cracks don't rear their heads until true combustion temps and pressures are reached. These temps and pressures can't be matched in the test. Anyway I am going to pull the head again and check everything once more. If I can't find anything wrong I think I'll put on a new head. Any thoughts would be appreciated in regards to what I should be looking out for.
Keep this in mind ... :(Quote:
Originally Posted by Only ever owned landys Ed
There are plenty of "experts" out there /// but few who really who know what they are doing when it comes to these motors ;)
So .....
Post a photo of the head + gasket + block ... as you found it (no cleaning) after you take it apart :) ... and then go from there
Mike
;)
Rot, a magnetic flux text or an ultrasound done properly will reveal ANY crack and often imperfections in the metal itself (IE dense spots inclusions in the base metal or where the surfacing spec is changed from poor machining)
I agree Dave, but I recently had a reco head that after a 5 km test drive re pressurised and even hydraulic locked the engine after resting for 10 minutes:oQuote:
Originally Posted by Blknight.aus
It turned out it had a crack behind an inlet valve seat and was absolutely pouring in after engine reached operating temp and pressure, (Steam train impression...)and under boost it would pressurise the cooling system aswell. It was a very unsatisfactory situation in the least:mad::mad::mad::mad:
The head, according to the machine shop was pressure tested and obviously surface ground, but still after tensioning down and running up it developed this humungous crack:mad::mad:
I have now started recommending NEW heads for Td5's that have been hot.
JC
to have a WAG....
bet it was a stressing fault... if it survived a pressure test (assuming that was competently done) that wasnt done on an artifical block with a reasonable presentation of torque and some heat (100 deg water circutlating the cooling jacket for about 1hr) it could have opened up as soon as the head was torqued down or heat loaded. Happens a lot with ricers but they generally use heads that are a dime a dozen and a lot easier to pull down and put up than a TD5....
Makes me miss my old "here is a chunk of cast iron we have drilled some holes in and installed valves and a sparkplug/injector, dont drop it on the floor, we value the floor to much" heads and blocks.
:D:D:D:D Too right!!Quote:
Originally Posted by Blknight.aus
I have an associate that is determined to buy a 2000 to 2002 130 and turf the Td5 an pay me to find and fit a 4BD1T to it:o He has owned a Tdi 130 since new in '98 and travelled most of this country in it about 390K now. He has a pathalogical hatred of ECU's but wants a neat late model vehicle with a dinosaur unbreakable engine in it....'Have I got an idea for you..." was my reply:D:D:D:D:D
The destressing of these Td5 heads I believe is mandatory after an overheat/ warpage since I saw that one:( You are correct in assuming it is a residual stress fracture, it sure looks that way.
So Dave, What are your feelings on replacing with new after a decent overheat? Cost currently is about $1300 over the price of a Reco....I'm thinking go new to avoid any issues etc as that $1300 could be the difference between enjoyning a $15K pre planned remote area trip fully loaded etc and it becoming a nightmare you will never forget. Small price for peace of mind?
JC
JC