When I bought my GT-6 11 years ago it had a slight rod knock and marginal oil
pressure. THe local LBC parts supplier told me not to panic over it - "the TR
family of 6 cyl engines have very strong bottom ends". So I drove the car like
that for a couple of years. When I finally pulled off the oil pan to R&R the
rod and main bearings, I discovered that I had 3 spun rod bearings. On one of
the rods the bearing shell had broken into three (3) pieces another shell into
two pieces! This was discovered on a Saturday afternoon in the middle of summer
- I needed (wanted) the car back on the road by Monday morning. The crank had
minor grooves worn into it (guess less than .010) but the nominal diameter was
still in spec. The rod ends that had the spun bearings had significant grooves
worn into them but the tops of the ridges were still in spec. Being
adventuresome, and planning on replacing the engine with a 2.5L the following
year, I bedded the bearing shells into the damaged rod ends and rod caps with
epoxy. Arriving at work on the following Monday (in my GT-6), I related to
some of my colleagues that I had epoxied in the bearing shells. I was ridiculed
mercilessly, especially when I admitted that I did not even use high temp epoxy.
I only expected to drive the car an additional 5,000 miles till I swapped
engines.
Life being what it is, I could not afford to buy and rebuild a 2.5L engine the
next winter. THe following year I commuted to Europe during the winter and did
not have the time to rebuild an engine (and my AL flywheel from Paeco (no,
no,no) arrived 11 weeks later than promised and then had to be sent back
because it was not true). Three years and 30,000+ miles later I finally pulled
the GT-6 engine with its epoxied in bearings out of service. It was still
running good. Just before I drained out the fluids to pull the engine I thought
I would run it at WOT to see what would happen. Red line was a function of
valve float and after annoying the neighbors for 3 or 4 minutes I shut it down.
When I tore the engine down to inspect the old epoxied in bearing shells the
bearing surfaces looked very good and probably still had more than half a
service life left in them but the thrust washers had fallen out and the rear end
of the crank was wearing into the block.
Date: Sat, 3 Jun 2000 17:03:52 -0400
From: David Massey <105671.471@compuserve.com>
Subject:
Message text written by "Martin A. Secrest"
>My TR6 has low oil pressure and a bearing knock at hot idle. I've
>undertaken a bearing/oil pump/TW rebuild.
>Possibly as a result of this condition, the #4 main journal has a very
>slight ridge on it. (All the other journals are in good shape.) My plan
>here is to renew all the shells, and the oil pump, to get the car
>through perhaps another year before I yank the engine for a complete
>rebuild. Am I headed for trouble with this slight ridge on #4 main? Or
>can I get by with it for a while?
Is this ridge from contact with the crankshaft? Check the crank to see if
there are corresponding marks on it. Or take the cap to a machinist and
ask his opinion. I acn't comment without seeing it. The ridges may be
normal factory machining marks and if so all is OK. If there is no crank
damage and you do all this you can run the engine another 10 years before
you yank it. If there is crank damage you should yank it now.
I did this to my car some two or three years ago (see, I have forgotten how
long ago is was and it runs great!) and I have excelent oil pressure and
the engine is only lacking a head overhaul.
>Martin Secrest
Good luck, Martin. It's a fairly easy job and I think the factory had just
this service in mind when the engine was designed. Len Renkenberger (THE
TR6 guru) says that if you change the bearings and rings every 60,000 or so
miles the engine will run 200,000 miles without a major overhaul.
Dave Massey
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