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OP
John Moore
Luke Skywalker
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Cool! Will do.
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Oil Pan
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Gary Lloyd
Jedi Knight
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I never knew it before, but John D Weimer explained it to me. Plastigauge only shows half the story. The trouble with doing an 'in frame' refresh, is that you can not spin it as you add a part as you do on a bench! If you have a stretched main cap, it may not show and when you fire it up it may still knock!! I would be concerned about that John, if yours is making very much noise!! OH!! I have asked 2 good machine shops now and neither of them assemble with plastigauge!! I never used it on the last one I just did, but other than that, I always thought it told the whole story, so I faithfully used it!! I guess use the plastigauge, but it is not infallible!! GOOD LUCK MAN!!!! Pretty soon you will be
again!!!
For what it's worth, I haven't used Plastigage in years. I assemble the maincaps, with bearings installed, (or rods, whichever) and use a bore gauge to check the ID, mike the crank, and do the math. Taking measurements around the bearing will show concentricity, as well, something that Plastigage won't do. Just remember to divide the difference in the ID of the bearing and the OD of the crank by two, to give you actual clearance.
I realize that not everybody has a bore gauge, but I'd be willing to bet that the two machine shops mentioned earlier use this method. However, this couldn't be done with the engine in the car, for obvious reasons.
TTFN,
Jeff
I realize that not everybody has a bore gauge, but I'd be willing to bet that the two machine shops mentioned earlier use this method. However, this couldn't be done with the engine in the car, for obvious reasons.
TTFN,
Jeff
tony barnhill
Great Pumpkin - R.I.P
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To each his own...I'm not the best mechanic around but when I build an engine, it lasts! A good machine shop will give me a good engine for my assembly - I only use 1 shop & trust them without a question....plastiguage is my way of ensuring torque is correct & everything is going together as it should...course, I don't use a timing light either! But, I'd never put an engine together without plastiguaging it...the stuff is just too cheap not to use...I'd also never put an engine together without spinning it!
...&, every 50,000 its okay to change bearings in car...but rebuild? Pull it & do everything properly - the 1st time!
...&, every 50,000 its okay to change bearings in car...but rebuild? Pull it & do everything properly - the 1st time!
John Moore, You said:
"Tony here's the symptom. A few days ago a noticed a "chatter" when I first start my car. It is a mid to high metallic sound that will last for a few seconds then go away when the oil pressure goes up to normal (55-60# at idle). I thought it was the valves or tappets. And due to low oil and they were just being loud until the pressure went up and they got an oil bath. I lost about a qt and 1/2 after driving my first 500 miles."
I've noticed this too on my 71 MGB. I started to use more oil this year than any other year I've owned the car (about 20 years). I'm running through about a quart every 200 miles similar to you all of a sudden. I hear that same noise you mention when cold, but it disappears after a few seconds. I don't remember if this noise occured before my oil loss because I never really payed attention.
So I shouldn't run this car until I check the rod bearings??
"Tony here's the symptom. A few days ago a noticed a "chatter" when I first start my car. It is a mid to high metallic sound that will last for a few seconds then go away when the oil pressure goes up to normal (55-60# at idle). I thought it was the valves or tappets. And due to low oil and they were just being loud until the pressure went up and they got an oil bath. I lost about a qt and 1/2 after driving my first 500 miles."
I've noticed this too on my 71 MGB. I started to use more oil this year than any other year I've owned the car (about 20 years). I'm running through about a quart every 200 miles similar to you all of a sudden. I hear that same noise you mention when cold, but it disappears after a few seconds. I don't remember if this noise occured before my oil loss because I never really payed attention.
So I shouldn't run this car until I check the rod bearings??
Gary Lloyd
Jedi Knight
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Out of curiosity, would torque on a rod bearing effect the plastigauge?? I don't think so, because of two reasons, first off, you use it on 'pre-assembly' and when it is pulled and cleaned and assembled for real, it could be different torques if you weren't careful, right??? Secondly, when the rod is put together, it really wouldn't matter how much torque was used to get a reading. The cap touches the rod, right?? The torque just makes sure that the nut stays on!! OH!! this time I used Lochtite on the rod nuts, I believe Tom Bedenbaugh said he did that also!!
tony barnhill
Great Pumpkin - R.I.P
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Guys, pay attention to what Tom Bedenbaugh says...he's the expert!
...however, if an engine of mine is making strange noises from the bottom end, I pull it! 2 hours to get it out is child's play...&, if its making noises, its too late to just refresh the bearings....
...disassemble, take to good machine shop...bore, balance reciprocating parts, blueprint, have them check everything...when you get it back, all new parts torqued down just like it was the last time with plastiquage...then disassemble, clean & put back together for final time...plastiguage is cheap & easy to use &, though not 100%, gives one a good feel for how everything goes together!
But, every man has to build his engine the way he sees it!
...however, if an engine of mine is making strange noises from the bottom end, I pull it! 2 hours to get it out is child's play...&, if its making noises, its too late to just refresh the bearings....
...disassemble, take to good machine shop...bore, balance reciprocating parts, blueprint, have them check everything...when you get it back, all new parts torqued down just like it was the last time with plastiquage...then disassemble, clean & put back together for final time...plastiguage is cheap & easy to use &, though not 100%, gives one a good feel for how everything goes together!
But, every man has to build his engine the way he sees it!
Tom, Tony, et al;
This may be out of left field, but I recall my brother having identical symptoms on his '69 BGT. Nasty noises on start, increased oil consumption, etc. When he tore it down, he found a bunch of broken rings.
Does this sound like a viable possibility for the current problems being discussed?
Not being a "B" guy, I'm curious.
Jeff
This may be out of left field, but I recall my brother having identical symptoms on his '69 BGT. Nasty noises on start, increased oil consumption, etc. When he tore it down, he found a bunch of broken rings.
Does this sound like a viable possibility for the current problems being discussed?
Not being a "B" guy, I'm curious.
Jeff
Tony, could this be the reason we are going through so much oil?? Do worn rod bearings create oil loss??
Excuse my lack of knowlege, I'm still in preschool engine repair
- but learning. I'll have to decide if I want to do all this work myself or hire a professional. I want to try it, but I don't want any serious problems due to my inexperience. Removing the engine I can do (did it to an old 67 Mustang a long time ago) , but the rest I'm not sure.
Excuse my lack of knowlege, I'm still in preschool engine repair
Gary Lloyd
Jedi Knight
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This time when I got the pieces back, I had to send parts back 3 times altogether before I was satisfied!! I would walk in the door, and some of the guys would have to go somewhere in a real hurry!! Personally, I really don't care what they think of me!!! If I am paying for it, it will be done right! The only thing that I am saying, is double check everything, and just do not accept it because they say it is fine!! That is why Tony's advice about the plastigauge is really a good thing!!
OP
John Moore
Luke Skywalker
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Granted I'm a newb too. I understand how the bearings could make noise, but I don't thing they could cause the loss of oil. Sounds like Buyeye, JohnnyC and I have described a similar problem.
[ 08-29-2003: Message edited by: John Moore ]</p>
[ 08-29-2003: Message edited by: John Moore ]</p>
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John,
When rod bearings get worn there is more clearance between the rod & crankshaft. This lets more than the usual amount of pressurized oil in the crankshaft leak out. This extra oil is thrown up onto the cylinder walls & can overload the oil rings & increase oil burning.
D
When rod bearings get worn there is more clearance between the rod & crankshaft. This lets more than the usual amount of pressurized oil in the crankshaft leak out. This extra oil is thrown up onto the cylinder walls & can overload the oil rings & increase oil burning.
D
Gary Lloyd
Jedi Knight
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I have never heard of that Dave!! The squirt hole in the top if the connecting rod is to lubricate the cylinder wall on the pressure side!(so I was told by the machine shop). Tom says that lack of compression doesn't have a whole lot to do with burning oil, I still haven't really figgered that one out, but I trust Tom!! My point is that if oil is squirted at the cylinder wall, how could a bad rod bearing make it burn oil?? If Tom says it does, then I'm on!! I think if there is a lack of oil pressure it will just kill everything real quick!!
Tom Bedenbaugh
Jedi Hopeful
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Boy, ya'll been busy on this one. As for plastigage I don't have anything against it, but I haven't done it except when I put an engine together and It felt too tight. My mach shop,knock on wood, hasn't screwed up yet.
I have never heard of worn rod bearing causing oil consumption. It does cause a loss of oil pressure especially after the oil get up to temp, and at idle.
What I said about compression was that having low compression doesn't mean you are burning oil. Matter of fact when oil get past the oil scraper rings and into the compression rings it will increase compression.
Replacing the rod bearing will buy you some time, Johnny, but there's a good chance the engine will need to be gone through totally down the road. While you have the pan off. Take a flash light and look at the cam lobes on each cyl. I'll put 10 to one odds that atleast one is bad. I have never open an MGB engine up yet that the cam didn't need replacing. It's because people don't keep them ajusted properly. They need to be check every 6,000 miles.
I have never heard of worn rod bearing causing oil consumption. It does cause a loss of oil pressure especially after the oil get up to temp, and at idle.
What I said about compression was that having low compression doesn't mean you are burning oil. Matter of fact when oil get past the oil scraper rings and into the compression rings it will increase compression.
Replacing the rod bearing will buy you some time, Johnny, but there's a good chance the engine will need to be gone through totally down the road. While you have the pan off. Take a flash light and look at the cam lobes on each cyl. I'll put 10 to one odds that atleast one is bad. I have never open an MGB engine up yet that the cam didn't need replacing. It's because people don't keep them ajusted properly. They need to be check every 6,000 miles.
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<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Gary Lloyd:
I have never heard of that Dave!! The squirt hole in the top if the connecting rod is to lubricate the cylinder wall on the pressure side!(so I was told by the machine shop). My point is that if oil is squirted at the cylinder wall, how could a bad rod bearing make it burn oil?? <hr></blockquote>
Gary,
Sorry to upset you. There are probably a lot of things that no one has ever heard of. Here is one reference by Hastings Piston Ring Co. There are references in other obscure auto engineering journals.
Certainly there may be a squirt hole in the rod, but if rod clearance is too great the squirt is too big for the oil ring to handle.
Check the last section of this reference.
https://www.hastingsmfg.com/Service%20Tips/factors_influencing_oil_con trol.htm#Crankshaft%20and%20Bearings
D
PS-- If you click on service tips index at the bottom there is a whole lot of interesting stuff.
[ 08-29-2003: Message edited by: Dave Russell ]</p>
I have never heard of that Dave!! The squirt hole in the top if the connecting rod is to lubricate the cylinder wall on the pressure side!(so I was told by the machine shop). My point is that if oil is squirted at the cylinder wall, how could a bad rod bearing make it burn oil?? <hr></blockquote>
Gary,
Sorry to upset you. There are probably a lot of things that no one has ever heard of. Here is one reference by Hastings Piston Ring Co. There are references in other obscure auto engineering journals.
Certainly there may be a squirt hole in the rod, but if rod clearance is too great the squirt is too big for the oil ring to handle.
Check the last section of this reference.
https://www.hastingsmfg.com/Service%20Tips/factors_influencing_oil_con trol.htm#Crankshaft%20and%20Bearings
D
PS-- If you click on service tips index at the bottom there is a whole lot of interesting stuff.
[ 08-29-2003: Message edited by: Dave Russell ]</p>
Gary Lloyd
Jedi Knight
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Heck, you never upset me!!! I read that article by Hasings and it definitely does say that that is a possibility!! Weird!!! Never heard of it before, but I would guess that most engines with worn bearings have worn rings too, so it could be a possibility!! Has anybody read this anywhere else???
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Gary,
It can happen without the oil rings being worn. Have you heard of or do you remember Smokey Yunick. One of the great race car & engine builders of all time.
A quote from a book he wrote in 1983 -- "Naturally you must have adequate oil delivery to the crankshaft & connecting rod bearings, but excess oil will be thrown off the crank & wind up on the cylinder walls. Under the best conditions, the oil rings have a difficult time scavenging oil from the cylinder walls. If excess oil is delivered to the walls, the oil rings will become flooded, oil will leak into the combustion chamber --"
A quote from another obscure source -- "Large end clearance is bad for a street engine because the rings can't handle the excesss oil thrown up on the cylinder walls. Under Full throttle the rings are "Tight" in their bores. In Light cruise conditions we run a hi vaccum in the cylinder and Oil control becomes a problem."
I realize that this is not too likely, I just mentioned the possibility. Something to think about.
D
It can happen without the oil rings being worn. Have you heard of or do you remember Smokey Yunick. One of the great race car & engine builders of all time.
A quote from a book he wrote in 1983 -- "Naturally you must have adequate oil delivery to the crankshaft & connecting rod bearings, but excess oil will be thrown off the crank & wind up on the cylinder walls. Under the best conditions, the oil rings have a difficult time scavenging oil from the cylinder walls. If excess oil is delivered to the walls, the oil rings will become flooded, oil will leak into the combustion chamber --"
A quote from another obscure source -- "Large end clearance is bad for a street engine because the rings can't handle the excesss oil thrown up on the cylinder walls. Under Full throttle the rings are "Tight" in their bores. In Light cruise conditions we run a hi vaccum in the cylinder and Oil control becomes a problem."
I realize that this is not too likely, I just mentioned the possibility. Something to think about.
D
Gary Lloyd
Jedi Knight
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Hey I appreciate it Dave!! I have never heard of that in my life!! That is why I love this and the MGB Experience so much!! A guy can learn so much if he will listen!! OH!! Smokey was one of the best engine builders, he could probably still teach these guys a thing or two!!
Hey Dave, can you do me a favour??? If you can stop by and see Loma and tell him I am finally running!! It is too hard to call because our hrs are soooo close!! I leave at about 6:00 am and don't get home 'til 5:30 our time!!
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Gary,
Sure I will go see Loma. He ended up with my first AH BN2 that I transplanted a V8 into. This was in the mid 60's.
Sure I will go see Loma. He ended up with my first AH BN2 that I transplanted a V8 into. This was in the mid 60's.