Timing Chain experience/knowledge?

ultimatequinoxe · August 22, 2020

Hi, I'll do a short and longer detailed version and hope the answers will help others too over time. I have searched online for hours and not got much useful info back. Here's hoping asking will help!

Short: 2006, GS450H Timing Chain.

1. How much slack is too much (or should there be none at all)?

2. Are green painted timing markers likely to indicate a replacement chain already (or are the green paint marks from factory)?

3. Does everyone pull the engine out to change the chin, or managed to change it in situ?

4. And most importantly, would someone mind confirming the correct timing mark position for the crankshaft (with engine in the car) - should the pulley mark be at about 2 O'clock position in line with the toothed timing marker extending from the engine block (marked "10" at the top?), or should the crank pulley be at about the 4 O'clock position, as it seems to be on the few video's I've watched regarding the 2GR-FE timing chain (with the pulley off and engine out)?

Further details, I bought the car a few days ago at a reasonable price with 151k miles, well looked after up to 2018 (based on receipt book and general condition). Service book is missing, but receipts show a fair bit of work with Lexus genuine parts, and MOT history is good. I bought it cheap knowing it had 1 definite issue (hybrid Battery cell failure) and one likely issue (the timing chain) - a project car with a steep learning curve if you will.

Drives nice, no breakdowns or mishaps over the 100 miles I've had to drive it. Just the lack of motor assist (going by the energy monitor anyway), and engine constantly on at any speed, getting about 29mpg average with mostly gentle B road cruising and a few half throttle blasts (any more throttle and I'll run out of road too quickly). No misfires, difficulty starting hot or cold, noses when cruising or accelerating etc etc.

But the engine does clatter on start up, and sounds to me a lot more like chain rattle rather than hydraulic lifter noise. It does have the fault code for Bank one sensor timing logged. I just spent the day carefully taking the cam cover off Bank one (left side of the engine when facing it from the front of the car) with some butt tense moments (The engineering on these newer GS's doesn't feel as sturdy to me as the 2JZ's did in the Gen 2 Lexus').

Timing on the gears appear to match up spot on, but there is certainly slack in the chains - I can lift the main drive chain and cam chain to a lesser extent about a centimetre off the gears in some positions of engine rotation. Maybe not enough to come off entirely, but feels close to a possible tooth jump to me if it went any more slack.

Plan for now is to go ahead and order a full service kit, sort the batteries out. Both hybrid cell/blade 16, and the Panasonic phase 3 12v Battery, which is not holding charge very well. Below about 10v and the engine won't start - I assume the cranking to start the engine comes from the MG1 and hybrid Battery I believe? But either way, when the 12v was taken off and fully charged to 13v, the car started fine - so it seems to have a bearing on the start sequence anyway. I figure the chain needs sorting asap, but how I go about doing that is undecided yet - I'd try it myself if it can stay in car, rather than have to be engine out. Otherwise, a decent indie garage may get the job.

If anyone has past experience or knowledge of the chain slack limit, and correct timing mark position on the crank (in line with the toothed timing marker, or further round?) it will help me a lot and help others too whom might be struggling to find this info. As these cars get older, DIY is surely getting more common place (even though they're not very easy to work on, and during these difficult times, saving money where possible is also prominent for many.

My many thanks in advance for reading this and pointing me/us in the right direction for correct info on the crank timing mark and chain slack, and anything else of relevance.

ColinBarber · August 22, 2020

Sounds like you have way too much slack in the chain. Take a look at the video linked to in this post which shows how much play he has, which appears to be 2 or 3 mm, and it also shows you the tensioner - you should check how far your one has extended.

Britprius · August 22, 2020

The chain can be changed without removing the engine, by taking off the cam covers, and the front timing chain cover. There are a number of video how to's on "Youtube" covering this,

If you do not wish to remove the front cover, and change timing chain guides.
It can also be done by splitting the chain over the off side "drivers side UK" timing sprocket after backing off the tensioner, and then attaching the new chain to the old with a split link. The engine is then wound over by hand making sure both ends of the chain remain in contact with the sprocket until the split link re appears at the sprocket. The link is then removed, and used to join the two ends of the new chain. A simple tool can be made to bolt to the cam housing to keep both sections of chain in contact with the sprocket. The tensioner is then released.
The tensioner can be got at through an inspection plate on the front of the timing cover.

ttps://www.youtube.com/results?search_query=lexus+v6+timing+chain

John.

Mihanicos · August 23, 2020

Always before you attempt to remove a timing chain, verify the engine's timing. The coloured links on the timing chains are to help their correct fitting. Rotate the engine from the cranksfaft pulley clockwise until the TDC timing mark is aligned with the pointer. The 10 mark is the cranksfaft position 10 degrees before the Top Dead Centre. Turn clockwise past this 10 degree mark and you should be at the TDC. The TDC mark on the crankshaft pulley should opposite the pointer.

The camshaft marks should align with the fixed marks opposite them. If not, rotate the engine another 360 degrees to align the camshaft marks. All inlet and exhaust valves on No1 cylinder should be closed.

If all the camshaft marks do not align with the reference marks on the engine, relevant to the TDC, then you have to replace the timing chain.

An easy way to verify the TDC of any engine is to remove the spark plug of No1 cylinder and put a long screwdriver in until it rests on the piston. As you rotate the engine, you will see the screwdriver reach a highest point and then it will begin to go down. The TDC mark on the crankshaft should be very close opposite the pointer.

From my experience, the tensioner and the guides of the chain should be good until an engine overhaul. But there are always exceptions.

If you opt out to change the timing chain, I agree with the recommendations of the other learned members. I would recommend a compressed link to close the chain instead of a clip. Clips run the risk of failing or coming off and that would mean another engine alltogether. You need a special tool to do this.

Chris.

Britprius · August 23, 2020

7 hours ago, Mihanicos said:

You need a special tool to do this.

You can buy a chain link splitter from most cycle, and motorcycle shops for very little money, and these will also re-fit the links without the need for a split link.
Using a split link in the chain replacement I outlined is much easier to do, and after the new chain is in position it may the be replaced using the tool. However in the past when timing chains were the norm they always came with a split link even from new. The only caveat is that the closed end of the spring link should face the direction of chain travel. Fitting the link with the open end facing the direction of travel runs the small risk of thick cold oil at high engine revs pushing the open spring link off the chain.

John

Britprius · August 23, 2020

It perhaps should be pointed out there are two more timing chains in the V6 engine. These are short chains that run between the adjacent inlet, and exhaust cams on each bank. These chains do no generally suffer as the load on them is small only driving one cam each against the load of all four cams being driven by the also much longer main chain. The short chains have there own independent tensioners, and are of the same size, and type of chain as the main chain.

John.

ultimatequinoxe · August 23, 2020

Big huge thanks to everyone for chipping in with top notch info!

I've spent the day carefully and slowly stripping more parts off to get the other rocker cover out (eventually, bleeding hands as proof). Moved the crank pulley round to "0", and certainly bank one seems out by a fair margin, though it was running okay, however the P0017 code was another sign of chain stretch.

I wasn't sure about an inspection plate at first, because it is entirely hidden behind a "drivers injection" module on the 450h's at least. Once that was off, I could see the plate was visible and certainly the tensioner piston shows signs of compensating for stretch.

I'd love to take the easier way and save a lot of effort and some risk, but my gut says the chain has been done before sometime ago, but with poor quality replacements. Seeing as its a potential engine killer, I've decided to carry on stripping and take the front cover off and do it all full on just to safe.

Just the thermostat housing and V-belt to remove today, then I'll do pulleys and front cover off tomorrow, and aim to complete the job in about a week (no rush, going slow to ease stress mistakes etc). Its quiet a job (for those thinking about it but never done it), and certainly time and decent tools are important.

A few pics added of the bank one gears and timing marks (with crank dead on 0 degrees at TDC). And a link to a short clip I took yesterday of the slack (sorry its all naff quality and clumsy; tired and using grandads inspection lamp). That slack in the video was before rotating the engine, now I've rotated it round a few times I don't seem to have any slack. However, the tensioner, P0017 code and 2 seconds of rattle on start up would seem to indicate the chain or chains are naffed. I guess when the engine stops after a run, there is a tiny bit of back (anti clockwise) rotation that gave me more slack as seen in the video.

Either way, not worth the risk, front cover off and do the lot for peace of mind and a more reliable miles out the car. MY thanks again, everyone's info has been very useful in getting me up to speed on these rather 'busy' and slightly fiddly engines.

https://youtu.be/P5ibY2fDMYA

Britprius · August 23, 2020

1 hour ago, ultimatequinoxe said:

I've decided to carry on stripping and take the front cover off and do it all full on just to safe.

If your going that far I would also replace the two VVT sprockets to make sure you eliminate the start up rattle. This could be the reason for the stretch in the chain as the hammering load on the chain must be considerable at start up. I say this because with the front cover off you have complete access to remove and refit the sprockets. You will be very disappointed if the noise is still there after all the work involved.
If the sprockets can be turned by hand a part of a turn without turning the cam with the chain removed they are faulty. There is a locking pin that should lock them when no oil pressure is present, and unlocks when there is pressure.
The new sprockets have a design change that is supposed to prevent the rattle reoccurring.

John.

ultimatequinoxe · August 23, 2020

Thanks, I'll add that to the list along with the water pump and a few other bits, like a crank pulley locking tool of some sort (if I can find one that fits) and another 22mm socket as the last one just cracked and the pulley bolt remains unmoved.

Britprius · August 23, 2020

2 hours ago, ultimatequinoxe said:

Thanks, I'll add that to the list

The belt tensioner bearings are standard bearings that are obtainable from bearing suppliers or eBay. The bearing number is "6203 RS" of witch there are two. The bolt that holds the pulley has a lefthand thread. The bearings can be pushed or tapped out after removing the centre sleeve "again can be pushed or tapped out". A pair of bearings will only cost about £5 against around £45 for a new pulley.

John.

ultimatequinoxe · August 26, 2020

Hit a snag and just needing to triple check - crank shaft pulley bolt is a left hand thread (turn clockwise to loosen)?

I know its been mentioned already (thanks John) but 3 busted sockets and a bent 2ft bar and still no joy in getting the bolt loose... which is jamming up the whole job.

Ps) Everything else off, sadly no air tools or power tools, only bars and brute force.

ColinBarber · August 26, 2020

Standard thread on the crank pulley bolt I believe.

It is the drive belt tensioner pulley bolt that is reverse thread.

Britprius · August 26, 2020

3 hours ago, ultimatequinoxe said:

no joy in getting the bolt loose... which is jamming up the whole job

Try going to your local tyre dealer, and see if they will loan you an electric impact wrench with suitable socket. That should shift it.

John.

ultimatequinoxe · August 27, 2020

Thanks for the replies as always!

Can't get the timing cover off as yet, not sure if its the sealant or I've missed one of the 23 bolts (and 2 nuts)? I thought I read somewhere that the belt tensioner hides one?..Anyway, sadly I found or somehow made a hole in the timing chain cover near the crank pulley; joyness.

But the pulley is off which was my main worry, anything else I can replace, sort... i.e be making progress rather than be at a dead stop, so I am not to bothered as yet.

It was fairly oily on the base of the cover and oil was low when I got the car, so I think that hole may have already been there and patched, and came off during the pulley removal process, maybe. Either way, it will be under pressure so slapping JB weld on it won't work for long (or at all) I guess. I figure I may have to order another cover from the states as I can't find any reasonably priced uk 2gr-fe covers for sale.

Needs a new water pump as the old one has been weeping and has excess bearing play. Add belt tensioner bearings and crank oil seal, maybe harmonic balancer/pulley and bolt too. Soon adds up! Meanwhile my 28 year old MR2 feels like a walk in the park to work on compared to the 450h - so sad it failed the mot on emissions or I'd likely not gone the hybrid route so soon and stuck with the old jallopy until next year.

ColinBarber · August 27, 2020

3 hours ago, ultimatequinoxe said:

I can't find any reasonably priced uk 2gr-fe covers for sale.

Be careful here, the 2GR-FE is similar to your engine but you have a 2GR-FSE and it seems the timing cover is a different part. The 2GR-FE is rare in the UK, it was only used on the RX350 which wasn't sold in great numbers hence you may struggle to find parts, but you don't want that anyway.

Do a bit of research to check but if the part code here is correct, it seems the cover is used on quite a few different models in the UK so it may be easier to find it as an IS250 cover for example:

ultimatequinoxe · August 27, 2020

Thanks very much! I really appreciate the top tips and guides. Just looking at some images too and the IS250 cover for exanple appears identical.

Although I 'could' get it welded or sealed with jb stuff, I realised its the oil pump pick up (I assume) on the reverse side, so if a patch blows out, so will the oil very rapidly.

....still cant get the cover off though... if its just the rtv holding it on I'd be amazed, but it feels like more bolts. I have all 23 bolts and 2 nuts front, 4 underneath and unhooked the aircon pump for any bolts behind that. I can feel about 3 oddly angled bolts on the tensioner mount but can't see if they are through into the cover plate as well. Very sloooooow process.

Ps) apollogies for typos and ignorance, life stuff, health and weather are draining me a bit.

Pps) Indeed a standard anti-clockwise to loosen crank bolt. I mssed the word 'not' when asking for confirmation, but can't edit it now.

ultimatequinoxe · August 27, 2020

Time to rethink....way too late sadly...

NB: to anyone thinking of doing this job on a 2gr-fse, NOT 2gr-fe. Eg gs450h etc..

The timing chain cover won't come off the same as a 2gr-fe, as the fse engines have internal oil pipes bolted up to the pump that need to come off or the front cover wont come out (as many find). Either engine out or do a lot of labour to remove subframe with engine supported to get to the oil pan bolts.

Found this 'how to' guide on a russian site (use translate and most of it is understandable)

https://www.drive2(blocked word)/b/518489827436397841/

This has not gone well. Used the car for one trip the day after I bought it and now it will be laid up for weeks - silly me.