Is the tdi an interference engine.

Rolo · December 23rd, 2007, 10:27

Does it eat valves when the timing belt breaks.?

bluesmoker · December 23rd, 2007, 10:27

yes

search the threads for broken tb

gern_blanston · December 23rd, 2007, 10:28

Most definitely an interference engine.

paramedick · December 23rd, 2007, 11:23

Absolutely. Bad things happen when the timing belt breaks or skips.

concours · December 23rd, 2007, 12:04

Welcome Rolo. YES, things go crash when they break. There are many, many mis-informed "mechanics" and dealerships floating around costing people thousands. You have stumbled upon THE very best forum for repair, maintenance and usage advice for TDI's. Read, read, read... and search, search, search... question EVERYTHING you've been told by the dealer. Collectively sharing ACCURATE technical info here has saved me thousands and many hours of troubleshooting time.

redneck_pilot86 · December 27th, 2007, 16:53

They are an interference engine, but a timing belt failure does not 100% guarantee a catastrophic engine failure. I had the tensioner let go on me, I guess the spring inside it slipped around about an inch and released the belt, the engine stalled and wouldnt start, but there was no damage to the head. I do beleive I am the exception to the rule though.

merkerguitars · December 27th, 2007, 19:57

Just ask Frank! Just make sure you do your timing belt on time (or early) and make sure you do it properly and you won't have to worry.

Turbo Dsl Beetle · December 28th, 2007, 05:35

Can I just say that with 20+ years in the automotive repair business I have never seen so much damage from any other engine when it's timing belt breaks.

Bobby

Franko6 · December 28th, 2007, 06:57

About what Redneck says...

The worst exception to the rule on skipped timing belts are the ones that you THOUGHT were non-strikes. Then, about a tankfull of fuel later, you are playing bongos with a valve head on a piston.

But yeah, I've seen a handful or so of crashed heads...

GoFaster · December 28th, 2007, 11:11

Quote:

Originally Posted by Turbo Dsl Beetle

Can I just say that with 20+ years in the automotive repair business I have never seen so much damage from any other engine when it's timing belt breaks.

Bobby

Really?

Seen what happens to a VW 1.8T, or practically any Honda engine, when its timing belt breaks?

On a TDI, *usually* it will smash up the lifters. The valves *usually* don't break off - although any valve that has taken a hit should be replaced anyway. The pistons, block, and the rest of the head are *usually* salvageable. I suspect it is because the pistons have a straight-line approach to the valves. YES, sometimes a valve will actually break off and wreak havoc. But on almost any engine with inclined valves, which includes practically every multivalve gasoline engine out there, a broken timing belt almost *always* results in breaking at least some of the valve heads off the stems, then the valve head bounces around in the combustion chamber and smashes up the pistons, the head, and scores the cylinder liners all to crap.

No matter ... the point is that if the timing belt breaks, badness occurs.

You can't build a 4-stroke diesel engine that is *not* an interference design.

AndyBees · December 28th, 2007, 18:23

Yeah, my cousin's '99 Beetle sort of survived major destruction when a section of teeth ripped off the TB at about 45 mph. In fact, we installed a new TB and the engine ran fine ... for a few days.

A general visual inspection did not reveal the obvious damage to the lifters (cam followers).

The damage to the head occured when the damaged lifters broke to pieces after we installed the new TB (in less than 1,000 miles).

By the way, the TB had "supposedly" been changed according to the stealership where he purchased the Beetle. We concluded that the original TB had actually made it to 105k miles.

I think the '99 Beetle had a 60k TB from the factory. If that be the case, then there is a considerable amout of "safety" built into the change interval.

ArnoldHarris · December 29th, 2007, 18:08

Assuming all of the above,

1) What is the safe mileage interval with the factory-installed TDI timing belt?

2) What is the safe mileage interval with a replacement TDI timing belt?

3) How can a TDI owner check the condition of his timing belt?

4) How many hours are involved in timing belt replacement?

5) How many hours for timing belt replacement are specified in the VW dealer's shop manual?

6) What special tools are needed for replacement?

7) What other belts should be replaced at the same time?

8) What other replaceable engine parts are there for which the timing belt must be removed to get at them (water pump, oil pump, etc)?

9) What other questions need to be answered about this problem with interference engines in general, and VW TDI interference engines in particular?

Arnold Harris
Mount Horeb WI

(2006 VW Jetta TDI; 5-speed manual transmission; B5 user; 30,500 miles.)

paramedick · December 29th, 2007, 18:26

Quote:

Originally Posted by ArnoldHarris

Assuming all of the above,

1) What is the safe mileage interval with the factory-installed TDI timing belt?

2) What is the safe mileage interval with a replacement TDI timing belt?

3) How can a TDI owner check the condition of his timing belt?

4) How many hours are involved in timing belt replacement?

5) How many hours for timing belt replacement are specified in the VW dealer's shop manual?

6) What special tools are needed for replacement?

7) What other belts should be replaced at the same time?

8) What other replaceable engine parts are there for which the timing belt must be removed to get at them (water pump, oil pump, etc)?

9) What other questions need to be answered about this problem with interference engines in general, and VW TDI interference engines in particular?

Arnold Harris
Mount Horeb WI

(2006 VW Jetta TDI; 5-speed manual transmission; B5 user; 30,500 miles.)

WOW! A bunch of questions in one posting.

Generally, the timing belts are good for the rated duration for the vehicle. There is a possibility of a idler roller or tensioner failure, so you listen for odd noises in the timing belt path indicative of a problem.

Inspection of the TB is mandatory, IMHO. Remove the TB cover when you change the oil. Look for fraying, cracking, missing teeth, or unusual wear on the TB.

I have no clue how many hours VW rates a TB change for. Most of us that do it regularly can change a belt and all components in 3-6 hours.

When the TB is changed, all the idler rollers should be changed, as well as the water pump and tensioner. Camshaft and crankshaft seals need to be changed if there is any sign of leakage of oil. All accessory belts need to be replaced at the same time.

Your last question is interesting. I wasn't aware of any problem with interference engines if properly maintained. My answer is absolutely use the correct oil specified for your car. Absolutely change the TB when required.

Yes, there are special tools needed. Metalnerd sells all the tools you will need in kits. PD engined cars have some additional tools that are needed.

tdidieselbobny · December 29th, 2007, 20:00

Water pump every time on A4,every other time on A3/B4 TDI's.I don't know about the TB's on your year(A5 platform)-I believe change same items as the A4.

AndyBees · December 29th, 2007, 20:45

At 167,687 miles, I changed my TB for the second time.

At that TB change interval, I also replaced the water pump and all three idlers/rollers for the 1st time. And, of course, the tensioner and other belts were replaced too.

The seals and gaskets have not been changed to date (224k miles)... no oil leaking.

The old WP appeared very okay... not loose, not tight, not leaking!

But, one of the three idlers/rollers was definitely near the end of its life. The other two "felt" okay.

Obviously, there was nothing scientific about the inspections. But, its quite obvious these items can go past 150k miles.

Now, having said all that, when I changed my brothers TB at 86k, the WP was showing signs of leaking. The leaking was apparently very small since he had not had to add any coolant up to that point. Sure, the seal could have failed catastrophically at anytime.

I recall the early model VW Diesel water pumps were notorious to "weep" but never come to catastrophic failure. Or, at least in the 28 years I have driven the VW Diesel, I have not had a WP failure.

For those who cannot do their own TB change, etc., the best advice would be to change all those questionable pieces parts at the TB change.. just for peace of mind!

For those of us with the "know-how" and access to a place (garage) to do the work, we can do the inspections and make replacements as needed.

Sure, its a no brainer when it comes to the WP and idlers/rollers as far as the amount of work required to change them .... do it while you are there attitude must prevail when doing the TB change!