Little OT but engine related

IaGary · Mar 16, 2012

Friend of mine runs a used car sales/service center.

I was there yesterday and they were tearing down an engine that the timing belt broke on. When the belt broke going 70 MPH it caused damage in number 3 and 5 cylinders.Pretty good 6 year old car with 80,000 miles on it.

Why would any company build a engine where there would be interference with the valves and pistons when the belt breaks?

They know that belt isn"t going to last forever.

Stupidest thing I"ve heard of. And several engines are built this way.

Gary

robgIN · Mar 16, 2012

I agree, but on the computer simulation nothing like that ever happens. Cars are designed by engineers, without input frm people with real world experience.If they were designed by people who actually had to work on this stuff, it would be a much different world.

Dave in GA · Mar 16, 2012

I've worked on a lot of V8s and inline sixes and straight eights and the cams have all been gear or chain driven. I have never touched or had an inline 4. My son is hoping to buy a 1990s or early 2000s Ranger or S-10 this summer, with a 4-cylinder. I understand that these are timing belt engines, and I've heard horror stories about belts breaking and ruining engines because of the resulting valve and piston contact. Now I'm wondering if taking a risk on a used vehicle with a 4-banger is such a good idea. I agree that building an engine that will experience fatal internal damage when a belt breaks is not very customer friendly.

farmer boy · Mar 16, 2012

One of the reasons I like the Corolla/Camry over the Accord/Civic. It"s no big deal if the belt breaks on a Camry, other than not being able to move. On an Accord, it"s going to take alot more $$ to get that car on the road again. It isn"t exactly cheap to change a timing belt, it"s even worse when engine damage is the result of a broken timeing belt. 80000 miles is a joke. A belt should last atleast 100000 miles. Anything else is poor quality. Just my opinion.

keh · Mar 16, 2012

The 2005 Toyota Camry and Tacoma truck we own have timing chains. Both 4 cyl. Don't remember about the 2000 I owned, but previous Camrys had belts, as did the 4 cylinder Ranger and a couple of Mazda cars. Never had a timing belt break. Was pretty careful about changing belts. One DOHC Mazda broke a cam, and I got a book from the library and took the head off. Head had to have valves ground and a bent valve replaced. Not a fun job, but the nearly new belt had nothing to do with the problem.

The 4 cylinder Ranger engine was bulletproof, I never did change the timing belt(used truck).

Like Gary, I always thought it stupid to design an interference engine.

KEH

Anonymous-0 · Mar 16, 2012

Belts need to be changed on schedule. Most are 80k belts but will ususally go much farther. My wifes Civic broke a belt but it is a clearance design so no damage. My Jetta TDI can't be so they get changed on time buuuut it's $700+.

MichiganMH · Mar 16, 2012

Maybe its just that I am used to motorcycle engines with this situation, but I do not see the big deal with interference valves. On vehicles with timing belts, they are supposes to be changed at regular intervals (80-100k). But then again most people today do not even change their transmission fluid, let alone a timing belt. Belts today are a lot better then they were even 15 years ago.

Dean · Mar 16, 2012

The use of interference engines in production vehicles was pioneered by Japanese manufacturers. It was a conscious business decision rather than an oversight. Resulting damage is very rare IF one follows recommended service procedures.

Dean

RodinNS · Mar 16, 2012

Just about everything today has an interference fit engine... I'd imagine when they factor in needed compression ratios and the flow characteristics tehy need from the head... those requirements dictate that it's going to be an intereference fit.
Generally there is a recomendation that the belt be changed at 55-60K miles. VW in particular, with it's TDI engines required that. If you change the belt as recomended there is seldom a problem. If you don't... you're almost guarnanteed you need at least a head and probably pistons/rods.
They make an awful mess when they break.

Rod

Leroy · Mar 16, 2012

Even tho they are not interferance engines the V8 350 Chevy with the chain will destroy the valves when the chain goes. Had that happen in 96 on the 74 truck pulling the camper while in Ontario and home is Ohio. Now the 2.2 Chrysler when it broke no damage.

Fordfarmer · Mar 16, 2012

My brother has had two Rangers with the 2.3L 4-cylinder. I think he's broken belts on both... and no damage. Current one has 325,000+ miles.

Goose · Mar 16, 2012

You don't say what kind of car it is, but I'd suspect if you check the owner's manual it recommends the timing belt be replaced at 60,000 miles. For obvious reasons.

Running the gamut of manufacturers, interference engines with timing belts (as opposed to chains) is the rule rather than the exception, nowadays. No belt lasts forever. Some manufacturers recommend replacing the belt at 60K, some at 90K, but all have a recommendation. What any auto owner needs to do is READ AND COMPREHEND the owner's manual.

It never ceases to amaze me how people will spend a thousand bucks on computer equipment and spend weeks and months learning everything they can about it, but they'll spend twenty times that on a vehicle and won't bother to learn anything but how to turn the key and where to put the gasoline.

The lowly Ford Pinto has been much maligned, but on one of them if the timing belt broke--you replaced the timing belt, nothing more.

El Toro · Mar 16, 2012

Probably should have read their car manual. Most recommend 60k miles. I also had a belt break on a Pinto. Not bad to change and no engine damage as Goose posted. Hal

buickanddeere · Mar 16, 2012

Find any over head valve engine that isn't interference design. Timing belt engines have less drag/ friction which contributes to fuel efficiency. Engine is ruined because the cheap, lazy illiterate owner didn't read the operator's manual. An engine can also be ruined by not maintaing the oil sump level or a function filter. Belt, oil level or filter, what's the difference ?

dgasper · Mar 16, 2012

Had an 85 1/2 Escort with 1.9L 4 cyl. Water pump locked up and shucked the teeth off the timing belt. Replaced pump and timing belt, good to go 190,000 miles before I gave it away still running.

Anonymous-0 · Mar 16, 2012

My question has always been why don't any of these mechanics who complain about engineering become engineers? They already have the basic skills so why not go to school and get the credentials.

Mike (WA) · Mar 16, 2012

Was going to buy a used Honda Accord some years back for "the fleet" (3 kids of driving age still at home at the time), on which timing belt had broken and wrecked the head. Changing a head isn't such a big deal, and it was almost a give-away price. Luckily, I mentioned it to a gearhead friend before I bought- he suggested I locate a head in a wrecking yard first, and "good luck with that", he said. Good luck indeed- he knew that no Accord in any junkyard in America still had its head- all get sold to the guy at the top of the waiting list as soon as they come in.

Those were fun times- buying oil by the case for the kids' junker cars (standard criteria for addition to the fleet was "runs and drives"), teaching oil changing and minor repairs, etc. Daughter, especially, took to it- still drives 20 year old Subarus until they croak, always on the lookout for the next one. She got free rides home from college across the pass in winter, once she made it known that she would put the chains on if necessary, all by herself, and the other girls wouldn't have to lay in the snow or risk breaking a nail. She even had a little satchel with coveralls, groundcloth and pliers.

Anonymous-0 · Mar 16, 2012

Similar story ; sent a tool kit, hammer, pliers, electrical tape, nails, etc. with daughter. She was the most popular kid in the dorm, girls AND GUYS always asking her to help fix something. Guess all those aggravating questions and shadowing does pay off.

buickanddeere · Mar 16, 2012

How long did the d v belts used to last? How long do serpantine fan belts and timing belts operate in comparason? Belts have been much improved. Ever figure the number of revolutions that timing belt had made at 60,000 miles and the torque load it carries?

LJD · Mar 16, 2012

standardbyke22;4537323 said:
The vacuum pump is to the left of the injecton pump on the top of the motor right? Any way to test or service?

The vacuum pump is at the rear of the engine. If it was a gas V8, it's where the distributor would be.

The vacuum pump is made up of two pieces. The "drive" and the "vacuum pod." You cannot run the engine without the drive in place since it runs the engine oil pump. This section has bearings in it - along with a helical drive gear. The "pod" is just a tin can with check valves and a diaphram inside. This you can remove still run the engine.

I suggest you listen near it and see if the noise is coming from there. Stick a garden hose by it with the other end at one of your ears. If it IS the noise source - pull the pod off and see it it changes anything - but it the drive might leak a little oil with the pod off.

To check the drive - you'd have to remove it and inspect it visually - and you cannot run the engine with it off.

LJD · Mar 16, 2012

Woops! My computer (and me) just did something weird. Pasted something from an old post.

Car companies often recommend inspecting that belt every 30K miles. If any wear is evident they are supposed to be replaced. So, with this 80K car - was it inspected 20K miles ago and found to be perfect? I doubt it.

Since cars tend to have small high performance engines - with high lift cams and high-top pistons, valve clearances are very tight. Consumers seem to demand these sorts of engines.

Back in the early days of US cars with overhead cams - belts and sprockets were problems. That ended when US companies started copying the Japanese engines like Toyota and Datsun.

KF · Mar 16, 2012

I work in the auto industry. Cost, styling, and handling are well ahead of maintenance considerations. Do you see the advertisements touting a vehicle's ease of maintenance as its primary selling point?

Mike M · Mar 16, 2012

Buick had a V6 around 1985-1986 models that the timing CHAIN would jump and bend the valves. They used plastic teeth on the gears that would give out at any time. My sister had one. Fixed the chain and then you fire it up and see if the heads need to come off. Well I only had one bent valve on a front cyl. so I put the piston at TDC, removed the valve spring ,dial indicator on the valve stem, rotate to the high spot,then with the BFH give it whacks until it rotates true. Saved pulling the head off and ran fine !If the piston was good enough to bend it then it could straighten too !

brian brooks · Mar 16, 2012

the ford 4 banger motors are non interferance so the belt breaks no damage.

Bill(Wis) · Mar 16, 2012

Most if not all Toyotas built today have timing chains with no service interval specified. Those older Toyotas with timing belts have a 90k mile specified replacement.

wisbaker · Mar 16, 2012

We have interference engines because it is the most economical way to meet emission and economy standards mandated by the government AND still deliver performance expected by the consumer. I have a 2.3 Mustang replaced the belt once at 80,000 miles so I didn't get stranded, it shredded a belt & jumped time at 135,000 but it's not interference so no harm. Our Accord with 275,000 miles is on it's 4th belt, I had it changed religiously at 100,000 and 200,000 but the original water pump went out at 250,000 so we changed the belt with the pump. If it's still around coming up on 350,000 (unlikeley we don't use it much anymore) it'll get a new timing belt. Changing the belts on them is as important as changing the oil. Girls with tool kits- #1 daughter decided she was going to school one state over and got a scholarship that made it cost the same as in state here. Packed her up to go to school with antifreeze, oil and ATF in the trunk and a tire gauge in the glovebox, for her birthday she got a tool bag full of basic hand tools duct tape wire ties and fuses. Some of the guys at school are amazed she checks oil & fluids and tire pressure.

buickanddeere · Mar 16, 2012

I have a Buick V6 that wore the timing gear teeth off at 260,000 miles. Didn't bend or break anything..

Dave in GA · Mar 16, 2012

Retired gentleman across the street had an 80s Buick V6 and the plastic teeth on the gear shredded and he ended up with one messed up engine. He was so angry with Buick that he mailed that gear to Buick headquarters with a nasty letter.

Mike (WA) · Mar 16, 2012

Yep, kids all had tool kits in trunk and got oil and "custom mixed" antifreeze jugs, replenished whenever they came home. #1 son in Seattle got 33% (good to zero), #2 son and daughter both in eastern WA, so got 50/50.

Hey, with 3 in college, ya gotta be a cheapskate!

They're all on their own and doing fine now, and competing to see who DOESN'T have to take in the folks when we reach our dotage.

dhermesc · Mar 16, 2012

My 1984 Ford F150 had a 302 and a timing chain. At 80k the chain lost time and the valves hit the pistons. It bent the push rods (exhaust?) on one bank of cylinders. I had a similar experience with a 351W only a peice of the nylon broke off and jammed the oil pump causing a gear to shear on the distributor.

Ford used a nylon coating on their timing gears to make the engine run more quietly, when the nylon wore off it would lose time. The replacement gears are all steel.

So having a chain on the cam shaft does not solve your problems.

Brad Buchanan · Mar 16, 2012

Interesting. That engine is a pushrod V-8 and I can't remember ever hearing about one where the pistons got tangled up in the valves unless a cam much larger than stock was installed.

Just goes without sayin' ya learn somthing new every day!

buickanddeere · Mar 16, 2012

Come to think of it there was engine damage. Several push rods were bent.

old popper · Mar 16, 2012

Twenty years ago I had three children driving Escorts with 1.9 4 cyl engines. I asked the owner of the local Ford garage how long it took them to install a new timing belt? "Two mechanics, 1 whole day and part of the next". he said. Well, I says, the last one I did took me 4 1/2 hrs with my daughter handing me tools. "Hey," he says "want a job?" Nope I replied, you don't pay enough.

Eric in IL · Mar 16, 2012

I don't really like the concept of an interference engine, but I have been driving cars with them since 1987 without incident. All have been V.W. diesels, I change the timing belts myself at the recommended interval.

I guess after all the miles I have racked up on these engines, I just consider the work of changing the belt a necessary evil for driving a car that gets good mileage.

LJD · Mar 16, 2012

I've got two 91 Volkswagen 1.6 diesels. I check the belts every 50K and have changed a few at 150K when they looked a little worn. No real problems. Both have over 300K and run perfect.

The one thing that astounds me with the Volkswagens is the camshaft sprocket. It has a tapered bore and sits on a tapered shaft with NO keyway. I guess they did that so if a belt does break - it can freewheel instead of trashing the engine.

Eric in IL · Mar 16, 2012

I always thought the lack of a key on the camshaft sprocket was to allow using any belt (new or used) and still be able to time the valve train. I could be wrong, as I wonder how much, if any, stretching a belt has over its' useful life.

Sorry, I don't understand which part you think that if "freewheeling" will avert engine damage.

Leroy · Mar 16, 2012

Was stalk all the way. Just saying things that are not supposed to be able to happen will.

Don-Wi · Mar 16, 2012

I had the belt done in my 03 passat a couple months ago. 1.8T engine, recomended replacement at 105,000 miles. I pushed it to 110,000 but then I brought it in. Should be good for a good long while now.

Donovan from Wisconsin

RodinNS · Mar 17, 2012

I wouldn't depend on it to 'freewheel'. It won't. Seen the results of a broken belt on one of them.
You get to buy a new head.

Rod

Little OT but engine related

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