Engine damage

[tomucen]

Hi,

I am the proud owner of a 1979 Buick Century with the 301 Pontiac Engine. I just moved from Germany to Switzerland and wanted to take my Buick with me. The first 150 miles the car ran like a dream. Then, all of the sudden, she started backfiring and not responding to the accelarator. Then she died and wouldn't fire although the starter turned the engine. Then she backfired again and the starter wouldn't turn anymore.

The engine has 104 Kmls on the clock, all fluids were fairly new and in sufficient quantity. Last year, I replaced cap, rotor, plugs and wires. The battery was 2 days old, so was the starter solenoid.

My worry is that the engine does not turn over anymore which would indicate a blocked crankshaft. Could this happen? I am waiting for the car to be delivered to my house by the German automobile club (thank god for my membership) then I will see what could be done.

Has anyone here experienced something like this. Any hints what could have happened? Right now I am clueless.....

Best regards,

Tom

[The Old Guy]

The first thing to find out is if the engine is actually frozen up ,or is it just that the starter is not turning it. If you can turn the engine at the flywheel, you may find that you just have a wiring problem. Let us know what you find.

[ronvb]

Tom,

With all that back-firing I would first suspect the timing chain stretched then broke. It could be bound up in the timing case cover and thats why she won't turn over.

ronvb

[Reatta Man]

Agree. Backfiring while running is almost always a broken timing chain, or the roll pin in the distributor to cam gear stripped and is not moving the distributor. If the car will now not turn over, that moves the probability towards the timing chain.

I would also recommend not trying to turn it over until the timing cover is removed. If the chain is broken and a portion of the chain is jammed against a gear, it could break the front housing or a tooth off the gear if the engine does turn over.

Good luck. The damage so far is frustrating, but not permanent, so don't worry about serious damage to the engine.

Joe

[tomucen]

Thanks guys,

I'll wait until I get the car delivered and then I'll take a closer look and post the result. The chain has crossed my mind but I first discarded it because of the fairly low mileage the engine has. But I think you are right.

If the chain broke, wouldn't the pistons collide with the valves and practically destroy the engine?

Best regards,

Tom

1979 Buick Century V8 301

[Reatta Man]

Tom,

On newer engines, such as many of those found in foreign cars or domestic cars equipped with foreign designed engines, you are correct in assuming the failed chain would destroy the engine. These are called "interference" engines, where the valves would interfere with the movement of the pistons, or vice versa, if they were out of time and moving at high RPMs when the chain/belt breaks.

A list of engines including interference engines is located at:

http://www.gates.com/downloads/download_...folder=brochure

When you look at the list, the engines marked with an asterisk (*) are considered interference engines. The only Buicks I found were the older Skyhawks that used a couple of four cylinder engines. Keep in mind that this is a list of engines that use timing belts, not chains. Anyone with an engine that uses one or multiple timing chains should probably call a dealer for their brand to see if their engine is considered an interference engine.

Joe

[Guest imported_moopar2ya2]

I believe that list only refers to belt driven timing and not the chain driven ones. Handy list though.

[NTX5467]

I suspect that most OHV American V-8s will be "interference" in nature. Meaning that if the timing chain breaks, there could well be a few bent valves. A few bent valves don't "destroy" an engine unless they crack the affected pistons, which is not too common. Usually, a valve job (which the engine might have been getting ready to need anyway, with attention to valve guide clearances too) plus checking the push rods for straightness might be all that's needed to put things back in good working order.

With the OHC motors, the hydraulic lash adjusters probably don't have the "travel" that hydraulic valve lifters in OHV motors do. The additional internal travel might help limit potential damage in the OHV motors when valves might contact pistons. In many of the later low compression motors, it's not nearly as critical as it was in the old 10.0 compression ratio days as the piston top is much deeper "in the hole" and away from the valves at TDC. I concur, loss of power and backfiring is usually a timing chain issue, BUT could also be an ignition module that went away too (although that might not keep the engine from turning over--unless one of the backfires while cranking jammed the starter drive, possibly). Usually, when an engine "jumps time", the plastic timing gear portion of the cam sprocket fails and the timing jumps one notch retarded (lower power, backfiring) and then it can totally fail. Timing chains that break aren't that common, from my observations, but failed composite material (plastic on metal) cam sprokets for those general year of engines were. In some of the Buick V-8s, there was something about the oil pump drive/distributor interface that could cause problems suddenly, but not usually backfiring per se.

Just as the electric fuel pump can go away over time due to fuel filter restrictions, the ignition coil and module and distributor rotor can do similar if the ignition has to produce too much voltage to fire the plugs. The spring loaded carbon contact in an HEI cap does not have to be there to fire the plugs, BUT it'll make the coil work harder to produce the fire to jump the gap, hence more heat. No dielectric grease to provide the heat sink to keep the HEI igniton module cool will similarly cause the module to fail from getting too hot. I don't know if your system is the GM HEI unit, but these are just some ignition-related issues that can cause some of the symptoms you mentioned.

Enjoy!

NTX5467

[tomucen]

Hi Guys,

this morning, the Buick got delivered and we pushed it into my garage. It's great to have the car back, I really missed it.

Currently I am building up furniture and unpacking boxes in our new house. As soon as we are settled, I will open up the engine, take a close look and a few pics which I will post here.

Best regards,

Tom

1979 Buick Century V8 301

Sins, Switzerland