I have this vehicle in my shop with broken timing belt. I want to know if this is an interference engine.
CUSTOMER DECIDED TO HAVE TIMING BELT REPLACED AFTER I EXPLAINED EVERYTHING TO HER.
Short answer, even engines designated as “interference” don’t always bend the valves. It‘ a crap shoot. You can rotate the cam and then bring the piston up to TDC on a 1 of the cylinders and do a leak down test. You can do this before actually install a new belt. For me, I just replace the belt after informing the customer of the possibility of engine damage.
All Honda engines are interference except 3.0L & 3.2 which are Non-interference
As stated below, not all listed interference engines bend valves. It seems that most t-belts strip their teeth on start-up, without enough revs top do any real damage. Now, if they're flying down the highway and the belt goes, it's a whole different ballgame. Inform the customer of the possibility of damage and put a belt, etc on the car. Evaluate afterwards. Otherwise, as suggested below, leak…
The two I had both ran fine after a new belt. Easy to just put a belt on and verify. Tell customer you need pay for ½ labour of belt change just to diagnose the valves. If that is it, just add in the rest of the work. That worked well for us. Maybe you could put a camera into the plug holes looking for witness marks on the pistons?
Yes, it certainly is. In fact, one of my employee's daughter's had this exact vehicle and a timing belt broke. It ended up bending something like 15 of the 24 valves! Our local machine-shop overhauled the heads and it came out very good.
My AERA Engine Builders Software says yes it is interference. Like the others have mentioned there is always a chance that it did not bend valves but I would say it is pretty likely that it did :(
Remove valve cover. If any of the rocker arms are loose, you have a bent valve.
I honestly have never looked to see whether an engine is interference or not. I just do a leak down. That will tell you what you need to know.
Just as an interference motor will not always bend valves, even non-interference motors will bend valves depending on when the timing went haywire. There's no half hour to ‘put a belt on’ one of these! A leakdown (that you charge for) will tell you whether it needs to be torn down or not. Putting a belt on to find that the engine is trashed on a ten year old vehicle, just to inform the client…
If there's no timing belt, how are you going to perform a leak down test? Some valves my well be “open” yet not “bent” depending on where the cam ended up, right? Unless you are planning to remove valve covers and rotate the cam for each cylinder, or remove cam. All more involved than a simple leak down. What am I missing?
… Exactly James… on my daughter-in- law's ‘08 Cobalt( twin cams, 4 valves per cyl).. I removed the VC and turned the cams to where the lumps were UP… and it bent valves on all four cylinders (at least ONE per cyl)…wasn’t in good overall shape so it went to the Mexico man…(for cheap)… Dan
Tim, Dont take this wrong, because I respect you, and always appreciate you chiming in on things. A leak down test on all 6 in an Hour? I don't know, I must be old and slow. I couldn't do it. I can put a water pump and timing belt complete, in one of those, in just under 3 hours, so just putting a belt in may only take an hour and a half. It would take me an hour and a half at least to pull…
IDK. I've diagnosed a bunch of these over the years, usually because the shop put the belt on without checking, and now they have a miss. Heck, when I was wrenching fulltime, I saw it happen with all kinds of engines, interference or not. It makes it a ton easier to have a belt on it, I agree, to do a leakdown. But, this is a relatively easy engine to get the plugs out of, and you're going to…
Tim, I think we would be correct in charging at least an hour to an hour and a half for a leak down test. A compression test alone pays one whole hour on this one. If it is good, you still need to pull the front of the engine off to do the belt. If you just put on the belt without reassembly, you spent roughly about the same time and if the valves are not bent, you are ½ done the job. This is…
I think you read David's response wrong- he stated half labor not half hour. I had to reread it too. Also, I did have an Odyssey come in were tensioner failed and zero compression heard during cranking. I believe I did do cylinder 1 for leak down and it held and forewarned customer of possibility of undiscovered damage, but since covers had to be pulled to line things up, It did only take a half…
He has a different approach that has worked for him, than what I would do. I think that it gives higher expectations (on the part of the customer) that it might be OK, when you really don't know until it's already on…I think it would be doubly disappointing. But, that's just me. It's a couple hours labor either way.
My thought and what I did in my case was to rip it down-under the diagnostic phase- as depending on condition of vehicle/engine, when these situations arise, and with the predetetmined decesion that it's going to be repaired or replaced(engine) if valve damage did occur, that verifying sealing condition would be far more efficient with the belt on once number 1 cylinder was confirmed tight, just…
Have a great Holiday! Thanks for the chat, and I learned something along the way.
I would be interested if the vehicle was in motion when the belt broke. I have had about 8 of these over the years the only one that survived was the belt had broken at engine startup.
I had a 2012 Odyssey that customer explained was making noise from tensioner for weeks-died on highway at 75mph. Can't explain it but no valve damage after new belt and tensioner. Drove out.
I just fixed a Honda Pilot with a 3.5 that broke a timing belt. It bent 6 intake valves.
Honda engines are unforgiven when timing belt breaks or strips teeth.
Pull the spark plugs and check with a borescope to see if there are any marks on the piston. If there are do leakdown, if not your probably good.
So let us know what you learned in the end of all of this fun chitchat!
That, although I do diag for a living, there's more than one way to get a satisfactory answer.