Piston Seize

[Bruce J. Obbink]

I am writing this note on behalf of a friend of mine that I am trying to get interested in signing on to the TABC list. He has two TCs and a TD in his stable. He is the president of the Fresno California MGT Motoring Society. He has had some frustrating moments with his TD that someone might have some advice for him. His #two cylinder has caused a piston seize three times. He has had the engine done professionally with 30 over pistons. The last re-build they were sleeved. Last re-build used heptolite pistons that were domed with the machine shop removing a portion of the dome to bring the piston into compatible pressure with standard pistons. But even so, the other two times the seizure took place using standard pistons. He is wondering of the sleeve job took too much of the cylinder wall away and that particular chamber is not getting the proper cooling. In addition to the cylinder problem, he is unable to get more than 30# oil pressure. He claims the rod bearings are within tolerance and the main bearings are at the maximum clearance of one thou. The rocker bushings are new and there doesn't seem to be any difficulty with the gauge nor the pump. Any body have a thought or two they would care to share I am sending a copy of this to Jare and you might respond to him directly with a little push to get on board. Cc: Jare Chick jandjchick@msn.com Bruce

[Peter Pleitner]

Hi Bruce and Jare, Without inspection of seized piston and bore its rather difficult to advise. For example what is the scuff or wear pattern on the piston skirt? Did the piston crown get unusually hot? Or did the gudgeon (wrist) pin seize? Presumably it is safe to assume rings weren't the cause because the other three didn't seize and were equipped with the same rings and bore finish. Then there is the question about the condition of #2 connecting rod. Could it be bent? Seizing a piston could do that. Were #s 1, 3, and 4 re-worked each time? The fact the machining was done professionally means to me that money transferred hands, but does not necessarily imply adequate knowledge or care. A problem with the ignition or mixture in #2 could also fry or burn that piston crown each time possibly causing seizure of top ring(s). How about the oil squirt hole in the connecting rod, can't recall if so equipped - sorry. Just guessing at this point. Sorry. Its an uncommon problem. Cheers, Peter -----Original Message----- From: Bruce J. Obbink [mailto:bruceobbink@mbayweb.com] Sent: Thursday, April 05, 2001 10:58 AM To: TABC List Cc: Jare Chick Subject: [mg-tabc] Piston Seize I am writing this note on behalf of a friend of mine that I am trying to get interested in signing on to the TABC list. He has two TCs and a TD in his stable. He is the president of the Fresno California MGT Motoring Society. He has had some frustrating moments with his TD that someone might have some advice for him. His #two cylinder has caused a piston seize three times. He has had the engine done professionally with 30 over pistons. The last re-build they were sleeved. Last re-build used heptolite pistons that were domed with the machine shop removing a portion of the dome to bring the piston into compatible pressure with standard pistons. But even so, the other two times the seizure took place using standard pistons. He is wondering of the sleeve job took too much of the cylinder wall away and that particular chamber is not getting the proper cooling. In addition to the cylinder problem, he is unable to get more than 30# oil pressure. He claims the rod bearings are within tolerance and the main bearings are at the maximum clearance of one thou. The rocker bushings are new and there doesn't seem to be any difficulty with the gauge nor the pump. Any body have a thought or two they would care to share I am sending a copy of this to Jare and you might respond to him directly with a little push to get on board. Cc: Jare Chick jandjchick@msn.com Bruce Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[C Sherriff]

Message text written by "Bruce J. Obbink"

>His #two cylinder has caused a piston seize three times. He has had the

engine done professionally with 30 over pistons. The last re-build they were sleeved. Last re-build used heptolite pistons that were domed with the machine shop removing a portion of the dome to bring the piston into compatible pressure with standard pistons. But even so, the other two times the seizure took place using standard pistons. He is wondering of the sleeve job took too much of the cylinder wall away and that particular chamber is not getting the proper cooling. In addition to the cylinder problem, he is unable to get more than 30# oil pressure. He claims the rod bearings are within tolerance and the main bearings are at the maximum clearance of one thou. The rocker bushings are new and there doesn't seem to be any difficulty with the gauge nor the pump. Any body have a thought or two they would care to share

[Zissel-Kreuztal@t-online.de]

Hi Bruce, hi T-Typers, So much problems after a professional rebuilt? 1. Cylinder bore: If the holes to big for the pistons, you have to overbore them to +0.40" 2. Oil pressure: Who said that the rocker bushings are o.k.? The machine shop can failed there, too. A simple test: Let the engine run a moment until the oil is hot. Then switch it off and disconnect the oilpipe to the head. Plug the pipe on engine side. Let the engine run (have no fear, the engine run without damage for a while). If the pressure change to 60 - 70lbs you have a problem with the head, otherwise......... 3. Modifiing Hepolite pistons: The removed metal was there to raise the comression ratio. POWER ) The hole thing was constructed to distribute the heat regular all over the piston and get a controlled expansion into the optimal round shape. A change of the design destroy this feature. Greetings lozi, TC3762 "Bruce J. Obbink" schrieb:

> I am writing this note on behalf of a friend of mine that I am trying to get > interested in signing on to the TABC list. He has two TCs and a TD in his > stable. He is the president of the Fresno California MGT Motoring Society. > > He has had some frustrating moments with his TD that someone might have some > advice for him. > > His #two cylinder has caused a piston seize three times. He has had the > engine done professionally with 30 over pistons. The last re-build they were > sleeved. Last re-build used heptolite pistons that were domed with the > machine shop removing a portion of the dome to bring the piston into > compatible pressure with standard pistons. But even so, the other two times > the seizure took place using standard pistons. > > He is wondering of the sleeve job took too much of the cylinder wall away > and that particular chamber is not getting the proper cooling. > > In addition to the cylinder problem, he is unable to get more than 30# oil > pressure. He claims the rod bearings are within tolerance and the main > bearings are at the maximum clearance of one thou. The rocker bushings are > new and there doesn't seem to be any difficulty with the gauge nor the pump. > > Any body have a thought or two they would care to share > > I am sending a copy of this to Jare and you might respond to him directly > with a little push to get on board. > > Cc: Jare Chick jandjchick@msn.com > Bruce > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/