What did you change inthe engine before these problems began? Something
must have been changed. What clearances are you running on the mains and
the rods? What is the oil pressure in the main galley at 7,000 rpm with the
oil at 180 degrees? I would say that 230 degrees oil temp is far to high if
you have a well positioned oil cooler. There may be to much internal
friction in the engine causing the high temps. On one TR-4 engine that we
did, opening up the main bearing clearances from 1 3/4 thou to 2 1/2 thou
dropped the oil temp 50 degrees because it stopped the crank from touching
the bearing surfaces due to the inherent flex that goes with a 3 main
bearing crank. I realize that you have a 5 main crank so the "flex" may not
apply. To me 80 lbs. at idle seems to high. One general rule of thumb
guideline is 10 lbs. of oil pressure for every 1000 rpm of revs. In a TR we
violate this rule slightly to the high side using 90 psi at 6 to 6500 rpm.
It is possible, I have heard to ''wash out" bearing from grossly excessive
oil pressure. Good Luck in finding the problem. Please let us all know when
you find the culprit.
All this assumes that the oil pan and baffling are working well and are
not contributing to the problem by starving the engine of oil in turns or
especially under hard acceleration coming out of a turn.
It might help to talk to IPD in Oregon or Washington. If you need me to
I can give you their contact numbers.
They raced Volvos for years and were very successful.
Regards, Greg Solow
----- Original Message -----
From: JOHN HAMILTON <hamilton@mail.nfdc.net>
To: <vintage-race@autox.team.net>
Sent: Saturday, July 10, 1999 6:11 PM
Subject: Bearing Problems - Help!
> I'm stumped and so are all my friends. Have Volvo, B18 (1800cc) full
> race engine, Oberg filter, Accusump, baffled pan and big oil cooler,new
> high pressure pump. I'm on the third engine this year (one per race).
> Runs fine initially then eats both main and rod bearings.Engine is
> properly clearanced including endplay by a professional builder who is
> also at his wit's end. We have checked crank for straightness, line
> bored the mains, balanced and rebalanced the crank and entire
> reciprocating assembly and we still get bearing meltdown after, say an
> hour or so of racing. Assembly and reassembly are done under almost
> "clean room" conditions.Holds 80 lbs. of pressure at idle when new then
> drops when bearings start to go. Ran well at Mosport this past weekend
> and held pressure until last race when warning light went on and
> pressure was at 30 lbs. and going South. Oil temperature has been high
> at 240 - outside temperature was over 100. Oberg is full of bearing
> remains. We have also checked all passages for restrictions.There are
> approximately 7 quarts in the system. I run the engine above 7200 rpm's
> but have been doing that for twenty-five years without this kind of
> problem. Anybody have any ideas short of demonic possesion? I keep going
> back to the Oberg - cooler - Accusump circuit eventhough this setup has
> been on the car for five years without problems until this year. No
> notion is too wild. Winning idea gets team T-shirt and a percentage of
> saved psychiatric bills. Thanks in advance,
> John Hamilton
>
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