A friend of mine has an '87 E30 (325) and his timing chain broke while doing 65 mph on his way home from my house today. His car has 170,000 miles on it. I am wondering, with 77,000 miles on my 74 3.0CS (perhaps 177,000 as I bought my car without any mileage verification) should I replace my chain just to be safe? Is my friend's engine toast now?
timing chain failure
- Thread starter bill
- Start date
A friend of mine has an '87 E30 (325) and his timing chain broke while doing 65 mph on his way home from my house today. His car has 170,000 miles on it. I am wondering, with 77,000 miles on my 74 3.0CS (perhaps 177,000 as I bought my car without any mileage verification) should I replace my chain just to be safe? Is my friend's engine toast now?
x_atlas0
Well-Known Member
Your friend should have a M20 in there, which uses a timing belt, not a timing chain, which is what the M30 uses.
There are many examples of 200k+ M30s with their original timing hardware. You may as well replace it if you are rebuilding the engine, however.
There are many examples of 200k+ M30s with their original timing hardware. You may as well replace it if you are rebuilding the engine, however.
x_atlas0
Well-Known Member
Your friend should have a M20 in there, which uses a timing belt, not a timing chain, which is what the M30 uses.
There are many examples of 200k+ M30s with their original timing hardware. You may as well replace it if you are rebuilding the engine, however.
There are many examples of 200k+ M30s with their original timing hardware. You may as well replace it if you are rebuilding the engine, however.
Most likely his valves are bent... Sorry.
Most likely his valves are bent... Sorry.
m_thompson
Well-Known Member
bill said:
His belt should should have been replaced at 60,000 and 120,000 miles and would have been due at 180,000 miles. I bet that it wasn't replaced at 120,000 miles.
m_thompson
Well-Known Member
bill said:
His belt should should have been replaced at 60,000 and 120,000 miles and would have been due at 180,000 miles. I bet that it wasn't replaced at 120,000 miles.
All true
The chains are long-lived - even in the S38 motors. The belts are not - mine broke at 45K in my e30 iX (but BMW paid for all parts even though it was out of warranty
) - I change belts every 40-50K in the e30 (annoying but only about $200) - with an interference engine the valves are guaranteed to bend if the belt breaks even if you are going slowly.
The chains are long-lived - even in the S38 motors. The belts are not - mine broke at 45K in my e30 iX (but BMW paid for all parts even though it was out of warranty
) - I change belts every 40-50K in the e30 (annoying but only about $200) - with an interference engine the valves are guaranteed to bend if the belt breaks even if you are going slowly.
All true
The chains are long-lived - even in the S38 motors. The belts are not - mine broke at 45K in my e30 iX (but BMW paid for all parts even though it was out of warranty ) - I change belts every 40-50K in the e30 (annoying but only about $200) - with an interference engine the valves are guaranteed to bend if the belt breaks even if you are going slowly.
The chains are long-lived - even in the S38 motors. The belts are not - mine broke at 45K in my e30 iX (but BMW paid for all parts even though it was out of warranty
) - I change belts every 40-50K in the e30 (annoying but only about $200) - with an interference engine the valves are guaranteed to bend if the belt breaks even if you are going slowly.
MichaelP
Well-Known Member
sfdon said:
A fuller explanation is that the M20 in your friend's E30 is an interference engine, meaning that the valves and pistons overlap the same space when all is well with the timing belt. When the belt breaks, the pistons crash into the valves. Look for an M50? It's a common E30 swap these days.
The M30 in your coupe is not an interference engine, so if the chain breaks, fewer bad things happen (the operative word is fewer, though). And the M30 chain and sprockets are pretty stout, so at 70 to 80K miles it ought to be fine. My last 535is had 250K on a replacement chain and sprockets (dealer replaced at 100K), and it was still in decent shape.
MichaelP
Well-Known Member
sfdon said:
A fuller explanation is that the M20 in your friend's E30 is an interference engine, meaning that the valves and pistons overlap the same space when all is well with the timing belt. When the belt breaks, the pistons crash into the valves. Look for an M50? It's a common E30 swap these days.
The M30 in your coupe is not an interference engine, so if the chain breaks, fewer bad things happen (the operative word is fewer, though). And the M30 chain and sprockets are pretty stout, so at 70 to 80K miles it ought to be fine. My last 535is had 250K on a replacement chain and sprockets (dealer replaced at 100K), and it was still in decent shape.
timing BELT failure
Thanks for the responses everyone. My friend has had the damage assessed, and to his and my surprise his mechanic says all that has to be done is a valve job basically to replace the bent valves...$1000! I was sure it would have been more like $2-3,000...
Thanks for the responses everyone. My friend has had the damage assessed, and to his and my surprise his mechanic says all that has to be done is a valve job basically to replace the bent valves...$1000! I was sure it would have been more like $2-3,000...
timing BELT failure
Thanks for the responses everyone. My friend has had the damage assessed, and to his and my surprise his mechanic says all that has to be done is a valve job basically to replace the bent valves...$1000! I was sure it would have been more like $2-3,000...
Thanks for the responses everyone. My friend has had the damage assessed, and to his and my surprise his mechanic says all that has to be done is a valve job basically to replace the bent valves...$1000! I was sure it would have been more like $2-3,000...