Timing Belt Failure.

[Paulnb]

Hello All.

Well I am still running my beloved 1998 Avensis 1.8 GL 143kmiles and counting.

That is until 3 days ago when my timing belt snapped on the motorway and I just wanted to get a answer as I have been getting two different answers.

Two mechanics I have called say the 7A-FE engine according to their cambelt books is a interference engine but I have heard and read that it is a non interference engine, obviously if it is a interference engine it may not be worth mending as a lot of damage may have been done, but if it is a non interference engine then I may get away with a cheapish belt,tensioner,waterpump replacement job.

So please anyone with knowledge or personal experience of this happening with this engine to them give me a definite answer.

Thankyou Paul.

[FROSTYBALLS]

A Google search came up with the following:

http://www.toyotanation.com/forum/130-7th-generation-1993-1997/337471-interference-engines.html

http://en.wikipedia.org/wiki/Toyota_A_engine (scroll down to the 7A series)

[Konrad C]

The engine is non-interference, so just needs a new belt and if necessary a tensioner.

I followed FrostyBalls wiki link and right near the end of the description, in the paragraph on the 7A you find the statement about non-interference.

Since the valves will never come into contact with the pistons, plus the inlet cam is driven by gears off the exhaust cam locking them together, this engine should have no problems.

Another thing is that there may be timing overlap where the valves are open with the piston at top dead centre.

The water pump does not have to be changed, only remove the bolts holding the pulley to give clearance.

The only thing I would suggest is to fit a new belt and turn the engine by hand to feel the compression. That way you will know if your engine is okay before actually starting it.

I had a tensioner break on a Maestro at high speed, fitted a new one and running fine.

Better than a chain cam breaking!!

[barrie013]

Had a similar thing happen to me, no damage to the pistons or valves, but the belt whipped round and damaged something else (which I naturally can't remember), so if you're having the job done make sure the fitter checks everything and doesn't spring an expensive surprise on you when they are halfway through the job.

[Druid Boy]

I thought that, if the water pump is driven by the belt, it was a worthwhile precaution to change the water pump. The logic being that if the water pump seizes it will snap the belt. Is this not an issue on Toyotas?

[Paulnb]

Great big thanks to all the people who posted a reply.

I will find out what the damage if any is tommorow as the mechanic is coming to fit a new belt etc in the morning.

i will let you know what the outcome is, but hopefully from all your answers it should be ok.

Thanks again Paul.

[Konrad C]

I thought that, if the water pump is driven by the belt, it was a worthwhile precaution to change the water pump. The logic being that if the water pump seizes it will snap the belt. Is this not an issue on Toyotas?

I agree about changing water pump at the same time as the timing belt, if the timing belt drives the pump. I did that with the Vauxhalls I owned.

On the 7A-FE and 4A-FE engines the pump is driven by alternator belt not the timing belt. The water pump pulley then drives the power steering belt. The water pump pulley has to be unbolted from the water pump to access the bolts holding the timing belt cover. My water pump was changed 2 years ago.

My belt is due for change and all I need is the belt and may be the tensioner.

[andrewm1]

The timing belt does not drive the water pump on the 7AFE Engine

[Druid Boy]

See? That's the problem with reliable engines - I don't spend any time fixing them so learn very little about them.

[Konrad C]

The pre 2000 - 2 litre engines (petrol and diesel) water pumps are driven by the timing belt.

This can cause confusion when the smaller engine 4A-FE/7A-FE water pumps are not.

[Paulnb]

Hello.

Just a quick update, just got the car back and indeed no damage done by the belt breaking.

Just had a new one fitted and im back on the road the car none the worse for the problem.

God Bless Toyota's non interference engines.

Thanks again to all who gave advice.

[Konrad C]

Paul thanks for the feedback.

[Flakmann]

Konrad; Did Toyota ever offer a 4A-Fe (1.6) engined automatic Avensis?

If so, I want one!

[Konrad C]

Roald (or is it Ronald), no the 4A-FE was not offered with an auto gearbox. Neither did the diesel 2C-TE.

My handbook shows only the 7A-FE and 3S-FE comes with auto.

This may be due to weight of the body and the power losses. The engine would have to work hard and this would dent the economy.

Some posters in the past have commented that the 7A-FE was the minimum engine size and power of the gearbox at that time.

Now recent cars have put on even more weight, but the engines are smaller and the auto gearbox technology has improved.

Anyway the only difference between the 4A-FE and the 7A-FE is the longer stroke of the latter.

The 7A-FE will be your best bet.

[Flakmann]

Thanks for that Konrad. I did buy a `99 Avensis GS 1.8 Auto and I`m very pleased with it.

I certainly can`t complain about the performance of the 1762cc 7A-FE engine, and the finding and buying of a 1.6 similar car would be purely out of interest and evaluation.

But; as you rightly say, engine power output per size and autobox technology has moved on.

Thanks again, Roald (as in Dahl?)