Has anyone heard of this happening before? My car's a Mk1 Gs300 Sport.

I started the car this morning, after driving it yesterday with no problems. backing it out of the garage I heard a fanbelt squeal. "Ah.. I think, better check and change the belt soon." Then i realise the steering is heavy...

Popped the car back in the garage and popped the bonnet. The serpentine/fan belt was VERY loose. The belt itself was intact so my prime suspect was the tensioner pulley, sure enough it's moved to it's full extent (to take up the slack, which makes sense)

Then I noticed a metal ring laying on the cover panel at the bottom of the engine bay - it's the outer ring of the crankshaft pulley

The weird thing is the pulley ring doesn't look to have sheared. I don't know if it's normally a compression-fit or not but I'm guessing an entirely new crankshaft pulley will be needed. I'm also not sure how much work is going to be involved in replacing it. I'm guessing I can do it in situ, although it looks like it's going to be easier to remove the rad and front of the car..

I should have searched harder! Looks like it's not uncommon.. http://www.lexusownersclub.co.uk/forum/lofiversion/index.php/t32237.html

I decided int he end that this was an opportune time to change the cambelt, since it was on my list of things to do in the near future.

There are some instructions on one of the MkIV sites but I'll take some pics and post my own in case its useful to anyone in the future. It's been relatively quick to get to the cambelt and pulley - I've:
i) removed the battery and airbox
ii) drained the coolant and removed the radiator
iii) taken the engine front covers off, rotated the crankshaft until the cam and crank marks are lined up, then locked the cams with a cam-locking tool (it was for my K-engined Caterham, but seems to fit )

All in all about 1.5hrs work

I've ordered a new crankpulley (about £45) and full belt kit.

I'm not sure how to lock the engine though? I may need to raise the front of the car and have a squint underneath - is there some way of locking the flywheel through the transmission-case? Anyone got any info on how to do this?

Thanks in advance for any help..

The manual doesn't give any details regarding lock pins for the cams or crank. Just special tools to hold the cam or crank pulleys while the nut is undone. Not much help from the official procedure I'm afraid.

Hi TigerFish, thanks for the quick response. That pretty much confirms the conclusions I'd been coming to. I'll take a closer look at the pulley and see whether anything ingenious springs to mind. There's the old standby of a breaker bar against the floor whilst cranking the engine over, if it comes down to it I suppose.

Many thanks,
Darren

At the risk of posting a lot of chaff to this post, Since I've got the cams exposed, something's been bothering me..

With both cams at the TDC position (both have their markers at the 12 o'clock position), my crank pulley (the inner ring, which is still fine, is pointing at the 5 deg mark, rather than 0.

Everything I've read and been led to believe about cam timing, including an electronic manual on the GS300 suggests that the cams should be at 12 o'clock with the crank pulley at 0. Can anyone confirm this? The engine has always run fine, and continued to do so when i started stripping it down, so I'm thinking logically I should just put the new belt on with these settings, but it seems to go against what I've read..

Any help or advice gratefully received..

Darren

you got a new crank pulley for 45 quid.....erm where from, there over 200 from Toyota.

if you say second hand........dont bother fitting it.

get a new one

I can confirm that the manual says



However, I've not had the top cover off so can't say if the timing marks on the back cover, (No.4) cover, are actually dead on 12 o'clock or not.

Hi Mat,

Definitely not 2nd-hand. I don't want to be doing this again next week or more importantly, to have it happen again at high rpms.

I've just rechecked, it was actually £42.35 ex VAT. This was from Lexus Guildford.. I was surprised by the price because I was guessing it to be around the £100+ mark. We both said the word 'crankshaft pulley' a number of times and I quoted the chassis number.

I'll post more after I go to collect it on Saturday. No doubt it's a crankshaft pulley bolt or something... I think I'll also ring to check that we were both talking about the serpentine belt crankshaft pulley and not the cambelt crankshaft pulley...

Edited to add... Thanks for bringing this up - Lexus had omitted to say that of the 2 pulleys available they'd not asked and chosen the crankshaft cambelt pulley (why would I be more likely to need one of these?!). £203 ex VAT for the fanbelt part of the pulley with the harmonic damper in it. At least I won't have a wasted trip to go and pick it up now.. I also added a new crankshaft pulley bolt for good measure..I might as well do a thorough job.

excellent......good job i brought it up.

i had to change the one on the monster last year.......

I just checked, a new one from Lexus is £203 + vat so im not sure if its old wrote off stock they've sold you or from another supplier

Thanks for checking Chris!

yep, tallies with what I later found out..

Pics of the JZ crankshaft locking tool:

Click to view attachment

Click to view attachment

you have to be a member of TIF to see anything.....

Ooops!..... post edited.

Cheers GarethR