Author Topic: MELTED HEAD! EXPERTS REQUIRED!? (Read 3610 times)

Lord0pants · « **on:** February 19, 2007, 01:41:31 pm »

Hello gents- originally fielded this to CGTI but apparently I need your expert knowledge!

Anyway- I finally found a replacement engine/head for my JR 1.6TD.

Removed the head from the 'new' motor and noticed a small disc in the cylinder along with the pock-marking of detonation (only present in one cylinder).

It turns out that it was the 'precombustion chamber'! Apparently the extreme heat- as evidenced by the pock marks has melted the head around the 'precom' chamber and caused it to drop out.

Is there anyway to re affix the chamber- especially given the fact it's recess is deformed!? Any tips!? IS it vital in the function of the cylinder?

All help appreciated- I'm getting desperate!!

Alex

hipifreq · « **Reply #1 on:** February 19, 2007, 02:27:58 pm »

According to the Bentley the pre-chambers cannot be replaced, and the whole head needs to be replaced if one is toast.

One of the biggest problems I see is that even if you did get a pre-chamber and could somehow make it fit in the head, then it would stick out and need to be machined flat with the head.

burn_your_money · « **Reply #2 on:** February 19, 2007, 04:34:36 pm »

The Bentley also says to knock the pre-comb chambers out so they must be replaceable?
Wouldn't the head be severely warped though?

hipifreq · « **Reply #3 on:** February 19, 2007, 08:46:36 pm »

My Bentley does say to knock them out to clean them and check for problems. But after that it says that if one is cracked to replace the whole head as they cannot be replaced.

Lord0pants · « **Reply #4 on:** February 20, 2007, 12:22:47 am »

Hmmm,
Thankyou gentlemen.

The pre-chamber is fine- it's the head/precom moulding that is slightly deformed.
The head itself isn't warped- it's just this one small area!
I'll see if I can improvise... How does the Bentley say they refit? Do they just press in?

Failing that- I have ANOTHER cylinder head from my old car... This one has a damaged glowplug thread on one cylinder.... As a short-term measure, would it be possible to get a new plug welded into position- permanently in the head?

If only old TD heads weren't so bloody rare!

Thanks guys!

Alex

burn_your_money · « **Reply #5 on:** February 20, 2007, 05:31:27 am »

You'd be welding steel and aluminum, which I don't think is possible. Just use a NA head, as long as you aren't doing anything super insane it will hold up just fine. You might be able to use a helicoil.

hipifreq · « **Reply #6 on:** February 20, 2007, 07:33:45 pm »

Yeah, helicoil would be my suggestion on the glowplug threading. Welding stands a chance of damaging the glowplug, which defeats the purpose of putting it in there in the first place. Helicoils work really well in the soft aluminum which is easy to strip, especially if your working without a torque wrench (or one that's not calibrated) and go a little too tight.

For the pre-chambers, they're press in. Nothing special to get it in, just push it in with a _little_ help from a soft mallet is all it should take.

Is there a auto machine shop near you that you could ask for advice, or perhaps see if they could do something with the deformation?

Lord0pants · « **Reply #7 on:** February 21, 2007, 02:55:18 am »

Cheers guys- yeah, the machine shop were brilliant.
Depending on the damage they'll either helicoil it or re-weld and then re-cut the hole/thread.

Brilliant.
I'm just stuck with the bloody return pipe now!

Alex