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MG TD TF 1500 - Valve stem damage

What caused this? My guess is , it was the same ham handed "Expert" who put my head gasket in upside down (causing #3 piston to melt ) I could not figure out why I was getting blue smoke on idle with new valves , seals and guides. Still I am not sure how he manageged it. All eight were marked to a lesser degree. There was a " ticking " from this valve on warm up that I could not diagnose , so I pulled the head for a look see.
" Mr. Lucky "

K. McKenzie

Another Pic

K. McKenzie

Did your machinist ream your bronze guides to the correct diameter? I had bronze guides fitted to my prewar OHC MG engine and they were reamed to cast iron tolerances. They seized after about fifteen minutes running. Bronze guides need extra clearance due to greater expansion.

Cheers

Jan T
J Targosz

No , They are fine . I checked them all with a ball gauge. all the damage appears in the seal area and the top 3mm of the gudes . I have 1500 miles on these guides.
Regards, Keith
K. McKenzie

Maybe somebody used a brutal method of gripping the valves when grinding the seats.
Dave H
Dave Hill

I agree with Dave H. If it occurred from running there would be longitudinal damage.
That looks like vise-grip damage.

Jim B.
JA Benjamin

Kinda funny for a hardened valve stem to be galled up with a bronze guide. Looks like miss handling to me, if it had seized up by being too tight, could be wrong but, I would think the damage would have been further down the stem. PJ
Paul161

The first thing I though of was vise grip. I see Jim B concurs. I've actually see a guy grabbing a stem with pliers to pull it against the seat while lapping it in.

Normally a suction cup hand lapping tool or, although I don't really like it and it doesn't seem to do any damage, a low speed drill chucked on the stem.
JE Carroll

I think I agree with you both and considering the errors made by this "expert" this new finding is not beyond the realm of possibility .
It does look like miss handling. Very annoying that his errors are still showing up 2 years later !
Not sure about the vice grips though because the marks were only ever on one side of the valves.
Maybe using a hammer to release the keepers?
K. McKenzie

I'd tell the world who worked on the head, might save someone else some grief. JMHO. PJ
Paul161


Keith, are your upper spring retainers and keepers stock MG TD?

Here's a possibility about what could have caused the beginning of the damage to your valve stems. If a "C" clamp spring compressor was not adjusted correctly and was used to compress your springs, the upper retainer could have been canted and scraped the valve stem. Your retainers would have to have a sharp edge on the inner lower part that fits over the valve stem. If no oil was used, and spring pressure was high it might be possible to scrape the valve stem in one spot when the spring was compressed to install the keepers. I would recommend you inspect all of the retainers very carefully looking for a worn sharp edge that could gouge/scrape the stem.
I've never seen damaged stems like yours before, but I have replaced a few retainers that showed obvious wear where the keeper fit into the retainer and left a sharp edge in a few spots.

Richard Cameron

Since the damage is only on one side that would seem to rule out the vise grip theory. Perhaps he was using some sort of spring compressor that was pushing the retainers hard against the valve or, as you suggest, hammering on them.

Quite the mystery......
JE Carroll

Thanks Richard,
That sounds like the culprit!!
My " expert" sent the head out for guides but but assembled the springs himself. I have lambasted him on the internet , no lies or emotion just facts. I had wrongly hoped that an older expert would have more experience. Sadly, I think he must have onset Alzheimer's !
( sorry ,Alzheimer's is no joke but I could not resist )
Best Regards, Keith
K. McKenzie

This thread was discussed between 13/02/2016 and 14/02/2016

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