Motor swap or Rebuild?
 

Here is the story guys...about 14-16 months ago, my timing belt broke while driving. The RMPs were low enough it only did minor damage to the valves. After a compression test, 3 of the four cylinders were still holding at 180 while cylinder 3 was at 165. The car idled rough but lasted about 10-12 months after a timing belt replacement. After that 10-12 month period its slowly gotten worse. I now have to stay on the brake and gas when at stopped, to keep it from dying. I have a friend who had the same motor and said that it was the crank that was bad when he had that problem and they did a motor swap on his. Its time to get this fixed the right way instead of driving a ticking time bomb. What are you thoughts, rebuild? motor swap? Thanks guys!

Car:
97 Accord LX
194k miles
f22b2

Measure compression again? It might be if you had replaced the bent valve(s) back when it happened, you wouldn't have done further damage (erosion around the valve).

I don't see a reason to assume it's the crank. You know something happened with the valves, so pull the head & take a look.

i never replaced anything other than the timing belt...i have another motor sitting in my garage too. I am not mechanically inclined, i would be paying someone else to do it. What would i be looking for?

supposedly the second motor ran fine but leaked coolant, they were gonna change a head gasket but the owner decided to do an engine swap. i got it for 150 bucks.

Take the advice and measure the compression again. It's best to find out what's wrong with the current engine rather than swapping it with another engine that "supposedly ran fine but leaked coolant." It's a pretty good guess that your current engine has a bent valve or two and you have a potentially good head from your other engine that you can swap onto your current engine if necessary. If the compression is low and it's due to bent valve(s), pull the head and check the pistons for damage. If they're OK then it's unlikely that there's any crankshaft damage.

when we were working on the timing belt, we took the spark plugs out and looked down at the pistons, none had major damage, there were little nicks in the cyl 3 piston where it had hit something. they were like small scratches, some maybe 1-2 mm deep, not sure how much that would affect the motor though. Another thing i forgot to add in the first piece that makes me think the crank COULD have damage, when we first got it running, it was still running REAL rough. we took the harmonic balancer off the 2nd motor, and that was a small bandaid that helped a little.

Thanks for your continues input guys. I really appreciate everything you can help me with here.

As far as replacing the head, if i have to go that route. Do i only need a new head gasket or with that require an exhaust manifold gasket too? Any others? Also if i took the head off the other motor, should i have that taken to a shop to clean and what not first, or should i be able to pull it off and put it right on the motor in the car?

I have to say, the chances of the crank being damaged are so remote I cannot even begin to fathom the odds. The fact is that the crank is many-many-many times harder/stronger than the (relatively) soft pistons, and as such, it is the pistons which will absorb the shock and become damaged from a valve hit and not the rods or the crank.

On a completely different car (not a Honda) my dad broke a timing belt & bent all the valves. Pistons had nice marks on them and the compression was just about zero.

We replaced all the valves, didn't do ANYTHING to the crank, rods, bearings or rings. He had the car for another couple years & it was running when he sold it.

A head gasket set will have all the gaskets you need: head/intake/exhaust/valve cover/EGR/etc. Since the replacement head is coming from an engine that likely has a leaky head gasket, you should definitely have a machine shop check the head for flatness and have it machined if necessary.Crankshafts just break or the bearings start knocking. They can't make the engine run rough.