How I may have killed my 740 (more info)

  • Thread starter Thread starter jimb
  • Start date Start date
J

jimb

Fellow aficionados of the Brick

In an effort to remove the crank sensor from my 1990 740, I broke the
mounting ear off the engine (transmission).

While tapping the sensor to rotate it in the mounting hole to free it
up I hit the mounting ear.

Casting is designed with a very thin wall around the bore that the
sensor fits in and hence broke directly across the bore. I am actually
surprised at how thing the casting is.

Does anyone have any ideas about how to repair?

Pulling transmission is possible but certainly not convenient.

Has anyone else run across this?

All this an I hope the diagnosis of the original problem is correct.

No spark, no injectors, seemingingly open sensor (infinite
resistance).

************************************
I forgot in the first post:

740 Non-Turbo
5 speed
Regina/Rex systems
************************************

TIA

jimB
 
I am just about to do a clutch job on my 99' V70 T5 and I plan to take the
engine out instead of disconnecting the transmission in place. Judging from your
experience this may be a good idea, right?

-Peter
 
jimb said:
Fellow aficionados of the Brick

In an effort to remove the crank sensor from my 1990 740, I broke the
mounting ear off the engine (transmission).

While tapping the sensor to rotate it in the mounting hole to free it
up I hit the mounting ear.

Casting is designed with a very thin wall around the bore that the
sensor fits in and hence broke directly across the bore. I am actually
surprised at how thing the casting is.

Does anyone have any ideas about how to repair?
Click to expand...

Unless I have a mistaken idea about how the piece is broken, it sounds like
a job for JB Weld, a steel-filled epoxy. The repair area doesn't have to be
exceptionally strong and won't exceed the 450F temperature rating of JB
Weld.

There are a few considerations. The mating surfaces have to be scrupulously
clean - use brake cleaner or alcohol. When the epoxy is applied it will try
to invade the threaded part of the casting; you should be prepared to deal
with that. A tap would work, or if there isn't room to do that you can wax
the threads of the crank sensor and run that in and back out before the
epoxy sets.

The finished product is surprisingly strong.

Mike
 
Fellow aficionados of the Brick

In an effort to remove the crank sensor from my 1990 740, I broke the
mounting ear off the engine (transmission).

While tapping the sensor to rotate it in the mounting hole to free it
up I hit the mounting ear.

Casting is designed with a very thin wall around the bore that the
sensor fits in and hence broke directly across the bore. I am actually
surprised at how thing the casting is.

Does anyone have any ideas about how to repair?

Pulling transmission is possible but certainly not convenient.

Has anyone else run across this?

All this an I hope the diagnosis of the original problem is correct.

No spark, no injectors, seemingingly open sensor (infinite
resistance).

************************************
I forgot in the first post:

740 Non-Turbo
5 speed
Regina/Rex systems
************************************

TIA

jimB
Click to expand...
Since the two screws that will hold the new bracket in place are
concealed by the bell housing, the only way to replace it is to R&R the
transmission. :-(.

Bob
 
jimb said:
Fellow aficionados of the Brick

In an effort to remove the crank sensor from my 1990 740, I broke the
mounting ear off the engine (transmission).

While tapping the sensor to rotate it in the mounting hole to free it
up I hit the mounting ear.

Casting is designed with a very thin wall around the bore that the
sensor fits in and hence broke directly across the bore. I am actually
surprised at how thing the casting is.

Does anyone have any ideas about how to repair?

Pulling transmission is possible but certainly not convenient.

Has anyone else run across this?

All this an I hope the diagnosis of the original problem is correct.

No spark, no injectors, seemingingly open sensor (infinite
resistance).
Click to expand...


Hmm that could be a little tricky. Can you drill a hole through the
broken piece on each side straight into metal still on the engine? If
you can do that, then tap out the holes in the engine and ream the ones
in the broken piece a bit larger you could screw it back on.
 
I am just about to do a clutch job on my 99' V70 T5 and I plan to take the
engine out instead of disconnecting the transmission in place. Judging from your
experience this may be a good idea, right?
Click to expand...

totally different car so I couldn't say.

I was working on the ignition and did something hasty.

this is an in-line drive car.

jimB
 
concealed by the bell housing, the only way to replace it is to R&R the
transmission.
Click to expand...

I held my camera behind the engine and took some pictures.

I see that the bell-housing has a relief for the nuts that hold the
bracket.

I assume that you are telling me that there isn't enough room to get
the nuts and bracket off as I had hoped?

TIA

jimB
 
I held my camera behind the engine and took some pictures.

I see that the bell-housing has a relief for the nuts that hold the
bracket.

I assume that you are telling me that there isn't enough room to get
the nuts and bracket off as I had hoped?

TIA

jimB
Click to expand...
Yup. Wanna see the t-shirt?

Bob
 
Bob,

Yup. Wanna see the t-shirt?
Click to expand...

I was thinking of just pulling the transmission back by a bit.

Put some longer bolts in a couple of the holes to keep everything
lined up.

I am a designer and I was amazed at how crappy the part is. Also how
fused the sensor was in the hole.

Maybe JB Weld with a reinforcing plate is the answer.

TIA

jimB
 
Mike

Unless I have a mistaken idea about how the piece is broken, it sounds like
a job for JB Weld, a steel-filled epoxy. The repair area doesn't have to be
exceptionally strong and won't exceed the 450F temperature rating of JB
Weld.
Click to expand...

thanks for the tip!

I had never heard of JB Weld; you're the second person to suggest it.
When the epoxy is applied it will try
to invade the threaded part of the casting; you should be prepared to deal
with that. A tap would work, or if there isn't room to do that you can wax
the threads of the crank sensor and run that in and back out before the
epoxy sets.
Click to expand...

sensor is not threaded in so it shouldn't be an issue.

jimB
 
You must log in or register to reply here.
Back
Top