Non interference engine!

Firestar_3x · 23 Mar 2006 at 13:12

Regarding Cambelts and the such, according to several sources the 1.8 lump in my MX is non interference by design, so if the cambelt snaps I just get stranded someplace and don't wreck the engine, can anyone else confirm this?

Mark

Malachy · 23 Mar 2006 at 13:18

lada's have this too hahaha

L0rdMike · 23 Mar 2006 at 13:19

Thats the general idea, MR2's are the same but still dont think its worth the risk.

Firestar_3x · 23 Mar 2006 at 13:21

L0rdMike said:
Thats the general idea, MR2's are the same but still dont think its worth the risk.

Funny you should say that mike, i just googled your mr2 before you posted

The reason for this is that every 60,000 miles, Toyota recommends a cam belt change for the car and this is an engine out job. A Toyota main dealer can undertake this job for around £400. Fortunately the MR2 engine is whats known as a non-interference unit, so even if the belt does go, your valves wont collide expensively with your piston.

Great engine design tbh, just an extra safety net i suppose

kaiowas · 23 Mar 2006 at 13:26

L0rdMike said:
Thats the general idea, MR2's are the same but still dont think its worth the risk.

Is that the case with mk2s as well then? I knew the 4AGE was non-interference.

L0rdMike · 23 Mar 2006 at 13:26

Luckily though I wouldnt take it to a Toyota garage to get it done.

Id rather not risk it though and get it changed when it needed doing.

Yeah im sure the 3S engine is the same.

geiger · 23 Mar 2006 at 14:40

Risk of what though, the timing will be out shortly before it stalls and detonation is likely but thats nothing major for a second or so or could it turn nasty :confused:

ajgoodfellow · 23 Mar 2006 at 14:47

Testing whether it really works?

I don't know but having witnessed a cambelt snapping first hand and completely destroying the engine I'm a little wary

Clarkey · 23 Mar 2006 at 14:50

subaru engines are like this too. I don't see this as a reason not to swap a belt out though, it is inevitable that it will snap so you might as well change it and spare yourself the breakdown.

Morba · 23 Mar 2006 at 14:59

Clarkey said:
subaru engines are like this too. I don't see this as a reason not to swap a belt out though, it is inevitable that it will snap so you might as well change it and spare yourself the breakdown.

if you dont have good cover then i agree, or if you dont want to risk being stuck somewhere waiting to be picked up.

Firestar_3x · 23 Mar 2006 at 15:02

Reason i'm asking is the MX is a 99 on a V, mazda recently revised the cam change interval to 53k or 6 n a bit years, its coming up for a cam change soon but i was wondering it i could wait till its next service and do it all at the same time, its just had a mazda main dealer service 600miles ago.

Morba · 23 Mar 2006 at 15:09

i guess it depends on how many miles you will put on it before you actually service it.

53k miles isnt a limit, more a guideline imo

megakid · 23 Mar 2006 at 15:10

Sweet, didnt know the 3S engine was non-interference - another reason to opt for the GT4

geiger · 23 Mar 2006 at 15:57

Clarkey said:
subaru engines are like this too. I don't see this as a reason not to swap a belt out though, it is inevitable that it will snap so you might as well change it and spare yourself the breakdown.

To save money I guess, its not always a cheap service. I used to have it done for 40 labour + 10 for parts (as soon as I buy the car) but Ive heard its hundreds in most places

thedazman67 · 23 Mar 2006 at 18:26

the engine used in the paseo 5E-FE has this design so if the cambelt does snap it wont cause any engine damage. my cambelt is being changed on my next service at 53K change interval is at 60K might aswell get it done with the service.

thedazman

Third Opinion · 23 Mar 2006 at 19:10

Why didn't they just use an engine with a cam chain?

panthro · 23 Mar 2006 at 19:16

why dont all cars come with non-interference engines?

PardonTheWait · 23 Mar 2006 at 19:24

panthro said:
why dont all cars come with non-interference engines?

Presumably more expensive to design and manufacture.

OR a secret deal with kwik fit and piston manufacturers!

Scandal!

Dogbreath · 23 Mar 2006 at 19:38

megakid said:
Sweet, didnt know the 3S engine was non-interference - another reason to opt for the GT4

The 3SGTE is allegedly, but I know of 3SGE's that have had bent valves so I don't think they are. That would make sense as the 3SGTE has a lower compression.

It's not exactly simple to make a non-interference 16v engine with decent performance. The required combination of high valve lifts, longer duration and high compression are at odds with the requirement for plenty of valve clearance.

Sputnik II · 23 Mar 2006 at 19:50

Firestar_3x said:
Regarding Cambelts and the such, according to several sources the 1.8 lump in my MX is non interference by design, so if the cambelt snaps I just get stranded someplace and don't wreck the engine, can anyone else confirm this?

Mark

I broke a cambelt on an MX5 and it was fine after a new belt was fitted. The only thing that concerned me was it had only had a new belt 1000-ish miles beforehand. I've heard of a few people that have had belts fail soon after being replaced.