Thread: This is starting to drive me nuts

Originally Posted by Psimpson7

I am not totally convinced by that Dave. The head gasket cuts into the head face and I wouldn't be risking it. (I would never have risked it on my race engines running alloy heads, and head gaskets with fire rings)

I also think that generally the re-hardnening is unnecessary.

Rgds
Pete.

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...

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

Originally Posted by mike 90 RR

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.

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.

Originally Posted by Only ever owned landys Ed

Hi all,
I was speaking to a diesel expert in Adelaide and he thinks the problem may be a cracked head.... Anyway I am going to pull the head again and check everything once more...... Any thoughts would be appreciated in regards to what I should be looking out for.

Keep this in mind ...

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)

Originally Posted by Blknight.aus

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
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

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

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.