rebuilt engine seized?

Had an incident with a rebuilt enegine that was at 900 miles on the rebuild. Was driving yesterday morning, 45 mph, everything fine, 70# oil pressure, temp at 190 when all of a sudden there was a tick, tick, tick, then a clatter, and then the exact sound of driving over an aluminum can, and then the engine stopped. The sounds were in very quick succession tick,tick,tick,clatter,crush and then silence.

I immediately threw it into neutral and stopped. Opened the hood and eveything looked okay. Good oil level. Nothing broken or leaking. Had it towed to the shop that installed the engine. They weren't able to start tearing anything down, that will start on Monday. The owner did a quick visual inspection and nothing jumped out. One thing that seems weird is that the bottom end appears to turn okay (this was done carefully and slowly and slightly by the shop owner) but the rockers don't move at all.

The rebuilt engine is your standard .060 over early 18V package with a flowed head and mild cam. It had been working flawlessly. It was broken in correctly, head re-torked at 500 miles, no loss of oil, no high temps, great compression (175 on the button accross the board). The engine was rebuilt by a pro who knows MGBs, the parts were all top quality...arp, vernier, double roller chain, billet cam and hardened lifters, ae pistons, best avaliable tri-metal bearings, etc.

As I keep going over the sounds I heard (yeah, it's a bummer waking up at 3:30 on a Sunday morning because of a car engine), it seems like the clatter was a little like a chain sound. I'm wondering if there was some sort of catastrophic failure of the timing chain or timing gears.

Any best guesses?

Thanks.

r, Pat Neher
Alexandria, VA and Huffs Church, PA

Hi, it sounds like a failure in the cam drive if the crank turns and the valve gear does not move.
Could be a vernier cam gear if you have one. I have heard of problems with some aftermarket designs used on other makes of car. Otherwise probably the chain. At least you should be trouble free in the bearing/bore areas!
Matthew

My guess...

If the crank turns all the way or at least almost all the way and the rockers don't rock either the drive system or the cam itself died. I have never heard of a cam breaking in two and a normal sprocket and chain set doesn't give way without lots of miles. My evil eye goes to the vernier sprocket itself or the installation thereof said bit.

Very sorry to hear of your troubles. You obviously have a satchel of money io the thing and from your description I take it that you actually know what you bought and appreciate the effort put into it. :-(

You know the drill. Pull the timing cover, and if the the crank won't turn all the way or a valve stem and spring look odd, pull the head and inspect the piston crowns and head.

Hope it turns out to be something really tiny though.

Jack

Matthew and Jack,

Thanks for the replies. I'm thinking the vernier sprocket too. Will find out tomorrow and let you know.

r, Pat

Hap may have something to say on this. I think I remember him saying something about problems with the adjustable cam sprockets.

Hope nothing touched in the top end. Your post on the sound reminded me of my buddy that used to drag race an A Auto 69 Camaro and has always helped me build my engines. He always said you don't want things touching at 7 grand cause it'll go "Binga Banga BOOM!"

defective parts do happen! Probably just one of those things that happen, but shouldn't. Doesn't make it any better for the owner:((

I never had a vernier failure, there are several designs out there, one being the Kent unit, which has about 6-8 bolts to secure vernier cam sprocket, the Romac, Rollmaster brand, is pretty much the same design, a little different bolts and washer going into the vernier, and it's sprocket design is a little different as well, but basicly the same thing, and the Romac unit also comes with a $40 JWIS timing chain, not that it can't brake, but it about ten times better than any other timing chain offerings in the world. For the either one of these units to being not able to activate the camshaft, every one of it vernier fastners would have to back out and fall into the timing cover, if they were just loose the cam timing could change but only a maximum about 20 degrees, and would move around in that range, which would probably make the engine run like crap but not quit running. As I mentioned above I never had a failure with either unit and have years of experience with both styles. After getting my cam timing where I want and locked down, I remove one vernier sprocket bolt at a time, and red locktite it, this is something that has been carried over from racing, I have heard of folks bolts coming loose, more than likely because they were not properly tighten to begin with, , but my locktite method has never failed me, but then hell I locktite everything, racing and the vibrations teaches you to do that and I carried that theme over into my street engines.
There'a a another type of vernier that doesn't have complete degree by degree adjustment, but use dial pins to secure the vernier sprocket, these were billed as a total bullitproof replacement for the true vernier, but I've heard of those units giving problems with dial pins backng out, but I never use that type of unit myself ever.
Hearing what you are telling me, I can only think of two likely things that would cause the valvetrain not to be moving at all, either a broken timing chain or a sheared key way on either the crank or cam, I would be really shocked if it were all the bolts in the vernier had backed out and if so, I would look at that as being builder error. Don't get me wrong, I'm not beyond mistakes myself, it happens, we're only human, but I betting on the timing chain myself, that would probably account for the rattle you heard.
Unfortunately, a lot of things will have to have good looking at to assure there is no damage, you have to make sure you have no bent valves, pushrods, or rocker arms, than you have to worry that when and if the valvetrain's movement was balked, then you could have lifter or cam lobe damage, I would highly advice all that be taken into account.
Please keep us posted to what you find out.

I'm going for timing chain too - and a possible cause. I wonder if the builder forgot to release the tensioner? A rookie mistake, I agree - but as Hap pointed out, we can all make them!

As I recall it was a Romac vernier and chain. Basically I bought all the parts for the engine from APT Fast and there's nobody better. Again, I'll let the board know how it turns out. It's just an engine after all.

Heck, half of the JOs in my office are either in Iraq of Afghanistan or about to start their pipeline training to go over. I'm thinking they'd like to swap problems with me right now...

Remember that the tensioners that are readily available have experienced some failures. I've had two people tell me that the rubber rubbing block came right off their new tensioners (Rolon brand available from Moss, APT, everywhere.) Perhaps the tensioner failed, the chain slapped, the chain failed, the engine stopped... Just a guess based on the tick, tick, tick (chain slapping) crush (chain whacking up against the housing. Basil

Totally sorry to hear about this, but I like your "palms up" attitude. whatareyagunnado?

Take photos please so that we can all learn.

Hap, sorry for misquoteing you. I knew you had mentioned them previously.

I tend to agree with Hap 100% on this and yes.... a complete teardown of the engine is in order to make sure NOTHING else was damaged. I do differ with Hap on one point though, When it comes to things like vernier timing gears and other such with critical fasteners, rather than trusting "locktight" (which has been known to come loose) I prefer to drill the bolt heads and install lock-wire.... as lock-wire done correctly is pretty much 100%.....

BUT!!! another thing you NEED to consider is your oil...... and the current problems with todays oils that no longer contain zink (ZDDP)
The following is part of an article about the problems with todays oils and our flat-tappet engines

"A month or so ago I had a member of the Columbia Gorge MG Club bring a totally failed camshaft and lifters back to me that had only 900 miles on them!! I immediately contacted the camshaft re-grinder and asked how this could happen. They were well aware of this problem as they were starting to have many failures of this type. In the past, the lack of a molybdenum disulfide camshaft assembly lubricant, at assembly, was about the only thing that could create this type of problem. My customer has assembled many engines and had lubricated the camshaft properly and followed correct break in procedures."

the full article is at this link;

http://www.capecodbritishcarclub.org/phpBB2/viewtopic.php?t=839

Michael

i would also consider the possiblility of having sucked a valve.

Well with the Kent vernier it would be nearly impossible to safety wire them because of the cup washers the machine allen bolts fit into, on the Rollmaster unit you could do though. I've been doing the red locktite method for some time with alot of race engines using both the Kent and Rollmaster, never had a failure, and I don't believe this is what he is going to find when he gets it apart, in fact I was the first vendor to import the Rollmaster unit to the US.

As for your buddies lifter and cam failure, let me guess a Delta reground, non hardened cam with standard lifters, that set up was begging to fail even with good oil. Hardened lifter and cams are for real, if you don't have them, you're simply rolling the dice, and hoping for the best.

Let me tell you a story, in the last year or so a very well known racing cam supplier ran into a deal where his cam grinder could no longer offer nitriting his reground cores to him, so he went with parkerizing instead, we saw about a half dozen cam lobe failures in one season, and everyone was using zinc enriched racing oil. Bottom line, racing or street engine you gotta have a nice hardened camshaft or Billet, and really good lifters. The standard stuff we used to buy used to be hardened properly and decent quality, from what I can tell from my own personal Rockwell C testing is standard lifters are not suitable for anything anymore.

As for leaving the chain tensioner not released , I rebuilt a MGB street engine about year ago, the engine a few years earlier by another shop, the engine had had been stripped on the front while left in the engine bay and a new duplex timing set had been install which included a new tensioner. Well when we disaasembled the engine, there was a new chain tensioner, still cocked shut and not touching the timing chain at all. This engine had been running ok, was smoking some, but running ok, and had been like this for about 5000 miles according to the owner. So what I gathered from that, was the timing chain tensioner while important for chain tension, bottom line the motor will continue to run without the use of one.

Update: No photos yet; I'm still at the puzzle palace today, but just got word from the shop that they pulled the timing cover and discovered the following: Broken timing chain and one bolt out of the Romac vernier and others loose. Don't know which happened first (bolt out or chain break) but they lean towards bolt backed out and caused chain failure. The dual vernier cam sprockets were very slightly out of alignment, they say. Working theory is bolt backs out, sprockets mis-align, chain breaks. I'll head out to the shop in the morning, meet the builder there, and take photos and post. Then they'll start checking eveything to assess extent of additional possible damage. Good news is that they don't think there was valve interference with the piston when the thing stopped. But they haven't started the close inspection and measurements yet.

The Builder at the machine shop is a solid guy...builds lots of mgb engines and various race engines...the parts supplier is a solid guy....and the shop is first rate. I think this will be sorted out satisfactorily. Should be able to to post photos tomorrow.

r, Pat

It's probably the cam chain or the cam gear.

Or, if you're really lucky it was just the key that locks it in place.

But, it's been my experience that when that key breaks that you still get SOME motion on the top end, just not in the correct time.

Cross your fingers that nothing hit inside the cylinders.

Good Luck

I know even less about computers than most other things, so excuse my ignorance on "floating threads" and the like. It looks like my last posted after B-Man even though it was sent in earlier.

I doubt UBL and Zawahiri have these problems.....but I digress....

Would be interested to hear from some of the engine builders out there, just how far down we should go to check for damage. My instinct says to take it down to parade rest, but that may just be based on 25 years in the NAV.

Thoughts, comments welcome.

r, Pat Neher

Nah - Unless you have a really wild cam, the valves in a B will not hit the pistons, so I doubt very much if there is any other damage. I would install new sprockets, and retime the cam. If you use a vernier sprocket, take Haps advice and Loctite the bolts.

The only other potential for damage is from the oil pump stopping (it is driven from the cam) - but since that coincided with the engine stopping (!) I doubt if there is any damage.

Eric,

Thanks for the reply. I just got back from inspecting the damage with the engine builder and shop mechanic. Will post photos when I get home tonight. Here's what happened: The builder did not put locktite on the bolts. One of the bolts came out, on the way out it made a nice round scratch ring on the inside of the timing cover, looks like it got on the outside of the chain, and it still had its washer. On the way around, the washer sliced thorugh the timing cover on the cam sprocket end just like a can opener. It looks like the bolt/washer then wedged down near the other end by the crank nose and cut the chain. Somewhere along the way, a couple teeth were chewed up. Thankfully it looks like no valve interference/contact with piston, but they're going to look with a scope through the spark plug hole to make sure. If it looks good, they will wash out the sump, replace the timing set and degree the cam again. By the way, the tensioner still looked good, but I think I'd like to replace it anyway. If everything looks good, the plan is to put in a new timing set, run a compression test, and if the numbers are good, fire it up.

Pat

Eric,

Thanks for the reply. I just got back from inspecting the damage with the engine builder and shop mechanic. Will post photos when I get home tonight. Here's what happened: The builder did not put locktite on the bolts. One of the bolts came out, on the way out it made a nice round scratch ring on the inside of the timing cover, looks like it got on the outside of the chain, and it still had its washer. On the way around, the washer sliced thorugh the timing cover on the cam sprocket end just like a can opener. It looks like the bolt/washer then wedged down near the other end by the crank nose and cut the chain. Somewhere along the way, a couple teeth were chewed up. Thankfully it looks like no valve interference/contact with piston, but they're going to look with a scope through the spark plug hole to make sure. If it looks good, they will wash out the sump, replace the timing set and degree the cam again. By the way, the tensioner still looked good, but I think I'd like to replace it anyway. If everything looks good, the plan is to run a compression test, and if the numbers are good, fire it up.

Pat

Eric,

Thanks for the reply. I just got back from inspecting the damage with the engine builder and shop mechanic. Will post photos when I get home tonight. Here's what happened: The builder did not put locktite on the bolts. One of the bolts came out, on the way out it made a nice round scratch ring on the inside of the timing cover, looks like it got on the outside of the chain, and it still had its washer. On the way around, the washer sliced thorugh the timing cover on the cam sprocket end just like a can opener. It looks like the bolt/washer then wedged down near the other end by the crank nose and cut the chain. Somewhere along the way, a couple teeth were chewed up. Thankfully it looks like no valve interference/contact with piston, but they're going to look with a scope through the spark plug holes to make sure. If it looks good, they will wash out the sump, replace the timing set and degree the cam again. By the way, the tensioner still looked good, but I think I'd like to replace it anyway. If everything looks good, the plan is to run a compression test, and if the numbers are good, fire it up.

Pat

Eric,

Thanks for the reply. I just got back from inspecting the damage with the engine builder and shop mechanic. Will post photos when I get home tonight. Here's what happened: The builder did not put locktite on the bolts. One of the bolts came out, on the way out it made a nice round scratch ring on the inside of the timing cover, looks like it got on the outside of the chain, and it still had its washer. On the way around, the washer sliced through the timing cover on the cam end just like a can opener. It looks like the bolt/washer then wedged down near the other end by the crank and cut the chain. Somewhere along the way, a couple teeth were chewed up. Thankfully it looks like no valve interference/contact with piston, but they're going to look with a scope through the spark plug holes to make sure. If it looks good, they will wash out the sump, replace the timing set and degree the cam again. By the way, the tensioner still looked good, but I think I'd like to replace it anyway. If everything looks good, the plan is to run a compression test, and if the numbers are good, fire it up.

Pat