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Old 7th October 2013, 14:37   #1
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Default Crankshaft problem

Hello Friends I need some expert opinion from the learned people/technical heads on this forum.

I have a stock gypsy 2006 MPFI model. My car had a oil pump failure and its crank was repaired (to .50 begen bearing). After the repair i notice three things. Firstly the knocking sound on idle was more prominent now(i think this was the crank sound like tak-tak-tak), secondly the engine oil red light instrument panel used show up for like 2 sec and then go away, this used happen all the time and more when i used to push the engine hard and thirdly when i went through gears on full throttle i never felt the rev cut.

After 300 km my engine's crank noise again increased and i found that the bearings have again gone bad, need crank repair again.

I am unable to figure out if the crank was not repaired well or was it because the rev limiter never worked and i over rev the engine.

And can any one tell me where is this rev limiter sensor on engine ?? and how can i know if the ECU has gone bad(if rev limiter is not working).

Can any one give me an idea how much will new crank cost ?
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Old 7th October 2013, 21:10   #2
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Default re: Crankshaft problem

If your engine is otherwise working, the ECU is (in all probability) working just fine.
Engine rpm is a derived/ calculated value.

You were WOTing and redlining an engine even when it was making strange noises?

MGP has 0.050 US bearings?

Get a half block. (Your mech has not done a proper job the first time. Doubt second time will be any better.) If there was a lubrication failure, also check the cam.

Regards
Sutripta
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Old 7th October 2013, 22:13   #3
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Default re: Crankshaft problem

Earlier the cam noise was something like a little more than normal but not abnormal, but yes i was redlining and revving hard. I drove for some 9-10 km through all in 2nd and 3rd in the red band. Engine did not cut(rev limiter) anytime.

And then i heard this loud voice, tak tak tak and i knew something went band.

Bearing size is more than stock must be .050, as mech told me its 50.

I'll get the CAM checked.

Any idea why i used to get the red oil light occasionally and why did not rev limiter work properly ?
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Old 7th October 2013, 22:22   #4
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Default re: Crankshaft problem

Quote:
Originally Posted by rishirich27 View Post
Hello Friends I need some expert opinion from the learned people/technical heads on this forum.

I have a stock gypsy 2006 MPFI model. My car had a oil pump failure and its crank was repaired (to .50 begen bearing). After the repair i notice three things. Firstly the knocking sound on idle was more prominent now(i think this was the crank sound like tak-tak-tak), secondly the engine oil red light instrument panel used show up for like 2 sec and then go away, this used happen all the time and more when i used to push the engine hard and thirdly when i went through gears on full throttle i never felt the rev cut.

After 300 km my engine's crank noise again increased and i found that the bearings have again gone bad, need crank repair again.

I am unable to figure out if the crank was not repaired well or was it because the rev limiter never worked and i over rev the engine.

And can any one tell me where is this rev limiter sensor on engine ?? and how can i know if the ECU has gone bad(if rev limiter is not working).

Can any one give me an idea how much will new crank cost ?
With due respect, I find it difficult to understand the possibility of development of crank problems/crank failure due to an oil pump failure. The oil pump is used to circulate engine oil through its walls; failure of the pump would only lead to starvation of the engine, eventually overheating it. How exactly can the crankshaft get damaged in such a situation is beyond me.

It seems that your mechanic made a wrong diagnosis and only harmed the crankshaft in the process. My advice is to contact your A.S.S/trusted workshop and get the crankshaft checked for any taper and twist. While you are at it, just get the journals and the bearings checked as well; you never know what might just be causing that knocking noise.

Regarding over-revving of the engine, even if you somehow managed to over-rev the car, the chances of piston and connecting rod damage would be higher than that of the crankshaft.

Also, IMHO, there is nothing such as a revv limiter sensor. Older cars came with a gyroscope to limit the revs to a certain level; modern ones rely on their ECUs to do the same.
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Old 8th October 2013, 09:39   #5
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Default re: Crankshaft problem

Quote:
Originally Posted by mohitk1993 View Post
With due respect, I find it difficult to understand the possibility of development of crank problems/crank failure due to an oil pump failure. The oil pump is used to circulate engine oil through its walls; failure of the pump would only lead to starvation of the engine, eventually overheating it. How exactly can the crankshaft get damaged in such a situation is beyond me.
Lack of oil will eat up the con-road bearings, and further lose oil pressure, This situation will damage the crank.

Quote:
you never know what might just be causing that knocking noise.
In this case, it might be con-road bearing conking off and hence the sound.

@Thread Starter,

As Sutripta suggested, get a half engine. IIRC, it will cost you ~27,000 and peace of mind is priceless!
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Old 8th October 2013, 21:14   #6
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Default re: Crankshaft problem

Quote:
Originally Posted by mohitk1993 View Post
With due respect, I find it difficult to understand the possibility of development of crank problems/crank failure due to an oil pump failure. The oil pump is used to circulate engine oil through its walls; failure of the pump would only lead to starvation of the engine, eventually overheating it. How exactly can the crankshaft get damaged in such a situation is beyond me.

....

Older cars came with a gyroscope to limit the revs to a certain level;
Hi,
I would have ignored your post but for its extremely confident tone. Went and also checked some of your other posts, say the ones on the combustion process. Might I suggest some more homework on your part.

Regards
Sutripta
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Old 8th October 2013, 21:58   #7
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Default re: Crankshaft problem

Quote:
Originally Posted by Sutripta View Post
Hi,
I would have ignored your post but for its extremely confident tone. Went and also checked some of your other posts, say the ones on the combustion process. Might I suggest some more homework on your part.

Regards
Sutripta
Hi there,

Forgive me for saying so, but I find little sense in your post. Having gone through my own post, I beg to be shown the so-called "extremely confident" tone used in it, as I seem to disagree. If you ask me, I have written it in plain formal English with a sincere desire to help the user in rectifying the issue.

Having seen Dhanush's post in the morning, I immediately went back to check the possibility of the same with some close friends of mine, only to find that the possibility of crank failure due to lack of oil is indeed possible. If you intended to bring that out, then yes, I'm sorry I did not know that.

Regarding my earlier posts, I would appreciate if you could highlight the ones where I may have been wrong. Personally speaking, I am willing to learn something new everyday and would not mind if I am corrected for any misinformation on my part.
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Old 8th October 2013, 22:01   #8
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Default re: Crankshaft problem

Quote:
Originally Posted by mohitk1993 View Post
With due respect, I find it difficult to understand the possibility of development of crank problems/crank failure due to an oil pump failure. The oil pump is used to circulate engine oil through its walls; failure of the pump would only lead to starvation of the engine, eventually overheating it. How exactly can the crankshaft get damaged in such a situation is beyond me.
Cranks run on journal bearings which need a constant supply of pressurized oil to work. First thing to fail in an oil starved engine is the crank bearings.
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Old 8th October 2013, 22:10   #9
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Default re: Crankshaft problem

Quote:
Originally Posted by mohitk1993 View Post
Hi there,

Forgive me for saying so, but I find little sense in your post.
Hi,
Then please ignore.

Regards
Sutripta
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Old 8th October 2013, 22:57   #10
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Default re: Crankshaft problem

Quote:
Originally Posted by rishirich27 View Post
Hello Friends I need some expert opinion from the learned people/technical heads on this forum.

I have a stock gypsy 2006 MPFI model. My car had a oil pump failure and its crank was repaired (to .50 begen bearing). After the repair i notice three things. Firstly the knocking sound on idle was more prominent now(i think this was the crank sound like tak-tak-tak), secondly the engine oil red light instrument panel used show up for like 2 sec and then go away, this used happen all the time and more when i used to push the engine hard and thirdly when i went through gears on full throttle i never felt the rev cut.

After 300 km my engine's crank noise again increased and i found that the bearings have again gone bad, need crank repair again.

I am unable to figure out if the crank was not repaired well or was it because the rev limiter never worked and i over rev the engine.

And can any one tell me where is this rev limiter sensor on engine ?? and how can i know if the ECU has gone bad(if rev limiter is not working).

Can any one give me an idea how much will new crank cost ?
New crank should cost around 5 to 6k approximately.

Did your mech/engine builder measure and use the right sized main and big end bearings? MGP sells a variety of bearings and choosing the perfect matching shell is by measuring the clearance and by matching numbers and letters on the crank, rods and the block. If there is a choice buying new MGP half block is a better lower end overhauling solution, especially if you like to drive its nuts off.

The rev limit on the G13 engine (not sure of the Gypsy's) is at 6500rpm, are you sure you have revved past this point? There is no rev limit sensor, ECU derives RPM signal from crank position sensor and it cuts fuel beyond 6500 RPM. I doubt rev limiter isn't working on the ECU.

Did you get oil pressure warning lamp when you revved near the redline? Is the oil level correct and are you using the right grade engine oil? Oil pressure shouldn't drop when you are near the redline. But with worn crank bearings it will drop.
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Old 9th October 2013, 08:43   #11
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Default re: Crankshaft problem

@sankar

where is this located "crank position sensor".

And yes i used get this oil warning light for a few seconds and it used to go off then, this used to happen when i pushed engine hard.

Since the oil pump failed i got a new one, can it be that this one was also not working well.
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Old 9th October 2013, 10:57   #12
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Default re: Crankshaft problem

@rishirich27 Since the Gypsy doesn't come with a OEM tachometer do you have a aftermarket tacho? Which aftermarket tacho did you use and is "no of cylinders" switch position it configured correctly to show the correct RPM? Not sure where the crank sensor on the Gypsy king, it could be at the pulley side, or in the distributor. If it was faulty you would have starting and running problems along with a check engine light.
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Old 9th October 2013, 19:01   #13
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Default re: Crankshaft problem

If you are pushing the engine regularly towards redline, make sure you do the following.
  • Decarb the engine to remove all sludge
  • check for leaks and fix
  • Test & overhaul the oil pump to make sure its in good shape. Put in an oil pressure gauge for peace of mind
  • Put in a new pump if necessary.
  • Use Synthetic oil
  • Run-in the engine after fitting new bearings
  • Get an oil cooler if necessary. Check with the rally crowd for options
  • Always keep an eye on the oil level and dont let it drop. High revving can cause oil to be consumed past the rings

Last edited by Mpower : 10th October 2013 at 18:33.
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Old 9th October 2013, 23:57   #14
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Default re: Crankshaft problem

Quote:
Originally Posted by mohitk1993 View Post
Older cars came with a gyroscope to limit the revs to a certain level; modern ones rely on their ECUs to do the same.
Err... Mohit, can you kindly list the names of a few cars where a gyroscope can be found? I've personally never seen one in any car.
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Old 10th October 2013, 19:12   #15
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Default re: Crankshaft problem

Quote:
Originally Posted by Mpower View Post
If you are pushing the engine regularly towards redline, make sure you do the following.
  • Test & overhaul the oil pump to make sure its in good shape. Put in an oil pressure gauge for peace of mind
  • Get an oil cooler if necessary. Check with the rally crowd for options
@Mpower

I had just got a new oil pump, it was a original MGP so very less chances if it might have failed.

How do i install a oil pressure gauge ?

Oil cooler i cannot put, and as such stock gypsies do perfectly well without it also.
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