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cutlass275

How Much Damage, Jumped Time On Timing Belt

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I've owned this 91 LS400 for about a 1 1/2 years or so. 82,000 miles when I bought it, 90,000 now. Had a sticker on the timing cover that had 7/09 as timing belt replacement. (Probably pretty close to the recommended 60,000 mile mark at the time), so I thought I was good. Few days ago, car just stopped cold, anti-freeze flowing out the bottom. I am very mechanically inclined, (built many motors, including race motors, NOT a Lexus motor), I can tell by the sound of the motor turning over it has jumped time. Not a broken belt I believe, but from the odd sound that most mechanics can identify as a car that has jumped time. ( it won't start, but does turn over, in an odd way) I realize the belt driven water pump probably created this issue, or visa versa, doesn't matter at this point...

New belt, waterpump, seals, labor will be $1000.00. *BUT, do I have bent valves?* THAT, is the question.

By the chart at my local mechanics shop indicates, this IS an interference motor. I was driving only about 50 mph at the time, not under acceleration (yes these things can matter). It would be a hassle, but possible perhaps to do a leak down on a few cylinders to determine if it has bent valves.

Does anyone have any experience on a 400 jumping time, or even breaking a belt ? What's your best guess on if I have bent valves or no ?

Thank you

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I've owned this 91 LS400 for about a 1 1/2 years or so. 82,000 miles when I bought it, 90,000 now. Had a sticker on the timing cover that had 7/09 as timing belt replacement. (Probably pretty close to the recommended 60,000 mile mark at the time), so I thought I was good. Few days ago, car just stopped cold, anti-freeze flowing out the bottom. I am very mechanically inclined, (built many motors, including race motors, NOT a Lexus motor), I can tell by the sound of the motor turning over it has jumped time. Not a broken belt I believe, but from the odd sound that most mechanics can identify as a car that has jumped time. ( it won't start, but does turn over, in an odd way) I realize the belt driven water pump probably created this issue, or visa versa, doesn't matter at this point...

New belt, waterpump, seals, labor will be $1000.00. *BUT, do I have bent valves?* THAT, is the question.

By the chart at my local mechanics shop indicates, this IS an interference motor. I was driving only about 50 mph at the time, not under acceleration (yes these things can matter). It would be a hassle, but possible perhaps to do a leak down on a few cylinders to determine if it has bent valves.

Does anyone have any experience on a 400 jumping time, or even breaking a belt ? What's your best guess on if I have bent valves or no ?

Thank you

If you do a simple search on this forum, you will discover that you do NOT have an interference fit engine. So, no bent valves (happy times). You indicate that the TB was replaced 7/09 and that you have owned the car for 1 1/2 years. So that places your purchase right around the time of the TB replacement or 82k miles. See if there are any codes before you determine that the belt has slipped. Heres is how to check codes -> http://www.lexls.com/tutorials/intro/codereading.html

A TB that is as new as yours should not break or slip unless the water pump seized (a real possibility given the antifreeze that you saw).

With antifreeze flowing out the bottom, you may indeed have a bad pump and, if so, might as well replace the TB, pump and pulleys. Being mechanically inclined, you can do this yourself for less than half of the shop cost. Good tutorials are available to guide you through. But a more thorough analysis (partial teardown perhaps) is needed before coming to that conclusion.

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As I have reported many times on this forum, the timing belt on my first LS400 - a 1990 - was trashed in the mid 1990's at about 75,000 miles when the water pump seized. Coolant flowed from the water pump when it seized.

By the way, the timing belt replacement interval is 90,000 miles (not 60,000 miles) or 6 years - whichever comes first. LS400 timing belts rarely break from fatigue. Usually another part in the system fails - water pump, idlers, tensioner, etc. These ancillary parts should always be replaced when the timing belt is replaced. I suspect that in your case the water pump was not replaced. If it was not replaced and the water pump is the original one, getting 20 years from it is a miracle.

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Thanks for the replies ! Wow, the mechanic shop I know has a big chart on the wall showing my motor is an interference motor. Your right, very happy if not !

I agree the water pump had to start the problem. Just because it had a sticker on the cover saying the TB was replaced on 7/09 doesn't really mean it was changed then, could have been a bit of a sales scam, really don't know. I did have a small amount of oil dripping from the front of the motor, a project that was going to wait till warmer weather. I suspect possibly one of the seals, which I will replace along with the idlers and tensioners etc. now that I know the valves are ok.

I just freshened my race motor, but that's a 403 Olds motor in a Stock eliminator drag car, (several world records and about 175 wins or R/U's) and built many chevy's, Dodge's, a ford or two...but wonder if I'm adept at an import like this. I admit I'm not the best at the tedious part of mechanic work, the race motors are easy to get to, no brackets or paraphernalia to work around :)

Thanks for the input from both of you, it really helped ! The code link is Gold, thanks !

PS, this car has always been garage kept and is in like new condition in and out. Only problem before this was the tach sticking, speedometer way off, and the usual clock display not easy to see. I have tried to read the threads on the clock display, it seems that the people that fix these go out of business as fast as they start. Larger problem now, those will wait..thanks...

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The LS, being a RWD vehicle with the engine mounted in-line, is really pretty easy to work on. Especially when you get the radiator out of the way. Once you get into it, I think you will be pleasantly surprised at how well the Lexus engine is designed and built.

I recently replaced the clock display on my 92 LS for $45. Again, fairly easy to do.

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Based on your prior knowledge and engine experience this should be a simple job for you. Maybe 8-12 hours in total if you take your time and keep records of where parts came from to aid in reassembly. I did my TB a few months ago and I've never rebuilt a race engine. Once you are in there changing the water pump is simple and it isn't that expensive. Camshaft and crankshaft seals are a little more work but they're not deal breakers. Since you have oil they fall into the "must do" bucket.

Here is my experience: us.lexusownersclub<dot>com/forums/index.php?showtopic=64500

As you can see there is a lot of help on the web to support this repair.

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Thanks for the encouragement, since this is an unexpected occurrence, the budget might require that I attempt the job.

Lander, 45$ sounds great on the clock fix. Did you do it at home, or send it off ? Can you share your fix with me ? (although it's on the back burner now)

CuriousB...I copied and pasted your link several times, comes up an error, I am very interested to see your experience. I've glanced at TB threads but so far haven't seen an actual Tutorial, although I haven't looked in earnest, mostly at the time looking for a post on bent valves. Will certainly need to find how to time the new belt, I have never worked on an overhead cam, nor twin cam motor.

Quick question...Harmonic Balancer, do I need a Chevy style puller (to use the bolt holes) or finger type...i.e. is there rubber in the Harmonic Balancer ?

(I have the finger type, my bolt on type got away thru the years) Perhaps it will be self evident when I look.

Thanks again for all the help, I'm guessing I'll be here asking a stupid question before I'm done...;)

PS...got plenty of metric tools etc, any special tools needed for this job ?

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CuriousB...I copied and pasted your link several times, comes up an error, I am very interested to see your experience. I've glanced at TB threads but so far haven't seen an actual Tutorial, although I haven't looked in earnest, mostly at the time looking for a post on bent valves. Will certainly need to find how to time the new belt, I have never worked on an overhead cam, nor twin cam motor.

Quick question...Harmonic Balancer, do I need a Chevy style puller (to use the bolt holes) or finger type...i.e. is there rubber in the Harmonic Balancer ?

(I have the finger type, my bolt on type got away thru the years) Perhaps it will be self evident when I look.

HB puller is nothing exotic. Some people use a simple steering wheel puller. I used a $10 HB puller from Harbor Freight. Threaded holes in "arms" of HB. I would recommend picking up a metric tap for these threads. It was hard to get bolt into the threads due to rust and grit. A couple turns with the proper tap would have cleaned it up. Tougher issue is getting the crank bolt loose. These can get pretty seized over time and very difficult to move. Mine was pretty easy but I think I was just lucky. I bought a special tool for this. Its shown in the link below.

Not sure the deal with links on this web site. It abbreviates them and so I remove the http part in front then they don't abbreviate then they don't work. Yopu think after 800 posts I'd have figured this out by now. Try the one below. http://us.lexusownersclub.com/forums/index.php?showtopic=64500&st=0&p=410434&fromsearch=1entry410434

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CuriousB...I copied and pasted your link several times, comes up an error, I am very interested to see your experience. I've glanced at TB threads but so far haven't seen an actual Tutorial, although I haven't looked in earnest, mostly at the time looking for a post on bent valves. Will certainly need to find how to time the new belt, I have never worked on an overhead cam, nor twin cam motor.

Quick question...Harmonic Balancer, do I need a Chevy style puller (to use the bolt holes) or finger type...i.e. is there rubber in the Harmonic Balancer ?

(I have the finger type, my bolt on type got away thru the years) Perhaps it will be self evident when I look.

HB puller is nothing exotic. Some people use a simple steering wheel puller. I used a $10 HB puller from Harbor Freight. Threaded holes in "arms" of HB. I would recommend picking up a metric tap for these threads. It was hard to get bolt into the threads due to rust and grit. A couple turns with the proper tap would have cleaned it up. Tougher issue is getting the crank bolt loose. These can get pretty seized over time and very difficult to move. Mine was pretty easy but I think I was just lucky. I bought a special tool for this. Its shown in the link below.

Not sure the deal with links on this web site. It abbreviates them and so I remove the http part in front then they don't abbreviate then they don't work. Yopu think after 800 posts I'd have figured this out by now. Try the one below. http://us.lexusownersclub.com/forums/index.php?showtopic=64500&st=0&p=410434&fromsearch=1entry410434

Hi. I think the problem with that link that doesn't work, is because he did a copy and paste. The actual post has <dot> and that doesn't work. If that is changed to an actual dot, it works:) Cheers, Keith

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Mile High....yep, I did copy and paste cause it wasn't a link....didn't really look it over very closely...put a "." where the DOT was...and it works...thanks...:)

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For the early LS, the link you will want is -> http://www.lexls.com/tutorials/engine/timingbelt.html

Concerning the clock display, you just get a new piece of LCD glass and install. The old one is trash. I got my new glass on Ebay -> http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=170447204098#ht_500wt_1182

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*UPDATE*....Just this week had time to jump on the timing belt project on my 91 LS400. The waterpump bearings had givin up, the WP shaft bent forward/down, and there went the TB. Worked about 4 evenings 4-5 hours per, didn't try to hurry (hence, no aggravation, lol)....and everything went beautifully. Hit the key, it cranked instantly and sounded wonderful ! Thanks for the help from all....

BUT...got a little problem. The car ran perfectly before the TB replacement.... Also sounded smooth when I cranked it up after I did the replacement, although I *thought* I heard a cylinder dropping a little as it sat in the garage when I was adding/checking fluids. Not bad though. Test drive, 5 miles, ran good, *although*, I still thought I felt a little weirdness. Started to rain, then the car surged, chugged, ran like crap. Push down on the gas peddle and it boggs, release the peddle a little and it picks up speed. Just ran crappy.

One of two things I think. I noticed the crank sensor not centered as I was working. Pushed against one side of the housing actually. I'm thinking that's the problem, but there was nothing broke. No indication it wasn't always like that. Should I take the sensor out and try to see if I can straighten it someway? it didn't look as though it was bent from the TB or anything, (belt was still on all the gears, just shredded a bit).

OR, one other possibility....I did leave the lower motor cover (the one under the car) off to watch for leaks for a few days, AND, I only lost one single part in this operation (was kinda proud I lost only one thing)...the little 1 inch diameter rubber plug that plugs the hole where the coil wire goes in to the left Distributor. Could the coil wire be this susceptible to moisture? Truthfully, I don't think it should be. Modern CD ignitions can usually literally take spraying a garden hose on em without missing.

I think it's the crank sensor, but don't know how critical and exact centered alignment is?

But the job itself, although time consuming, wasn't too bad. Thanks again.

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Could be crank position sensor.

I'd also double check cam timing. Turn harmonic balancer to TDC 0 degrees and open up the top copvers and see if the marks aline properly. If not turn HB it one full turn and check again. If they aren't exactly lined up you might have offset the timing belt one link and that spells trouble.

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Nope, the belt and all the timing line up perfectly. I noticed the crank sensor off center when I did the job, way over to the side of the housing, but didn't see any indication of damage, so thought it might have always been like that. I really don't see a way to straighten it out...wonder how perfect in the hole it needs to be? I'll look further...thanks Curious...

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Just lettin ya know (if anyone is interested lol) that I found my miss. A 5 second fix, (it's usually the simplest things). It felt just like a vacuum line left off of a carburetor in older cars...I knew I finished and test drove late at night, which means, yes, I left something simple unattached. The air flow meter that connects to the air intake. Plugged it in and Walla ! Runs perfect...

Thanks for the help and encouragement...next, when I get mentally prepared (lol) will start on the climate display.

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Awesome!

TB is pretty involved on these cars so you climbed a new moutaintop. You just saved about $1000 of dealer labor as well.

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As I have reported many times on this forum, the timing belt on my first LS400 - a 1990 - was trashed in the mid 1990's at about 75,000 miles when the water pump seized. Coolant flowed from the water pump when it seized.

By the way, the timing belt replacement interval is 90,000 miles (not 60,000 miles) or 6 years - whichever comes first. LS400 timing belts rarely break from fatigue. Usually another part in the system fails - water pump, idlers, tensioner, etc. These ancillary parts should always be replaced when the timing belt is replaced. I suspect that in your case the water pump was not replaced. If it was not replaced and the water pump is the original one, getting 20 years from it is a miracle.

I owned a 1991 LS400 for 12 years. The timing belt change interval in MY owners manual was 60,000 miles, NOT 90,000 miles. When the dealer replaced the TB he also replaced the water pump and charged for it under the extended power train warranty. I just had the TB of my 2002 LS430 changed and at almost 90,000 miles the extended power train warranty was only a memory. The dealer was not automatically going to replace the water pump but I insisted on that. Also, the dealer was not going to change the serpentine belt for the accessories! I had then do that as well. I was already paying for them to remove and install those items so it just seemed to make sense to have those other major wear items replaced for just the cost of the parts!

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