98 LS400 engine failure at 68000

[Lexuslvr]

I had a strange failure on my mint 98. No other problems previously.

It has always run great. But, last week I started it up and immediately noticed a loud ticking much like bad lifters. I shut the car down within 5 seconds.

My wife had backed it out of the garage the day before to get something out, and simply pulled it back in; everything was fine for her.

I checked the oil (fine) just changed 300 miles previous, and checked everything, and tried starting it again. Hard cranking...and gave up.

I think the timing belt may have jumped a tooth, but I have nightmares of bent valves from the 5 second run at startup.....

Has ANYONE heard of a similar failure, or offer any assistance?

I thought I might pull the cam covers to see if the belt snapped or ???

Nearest dealer Birmingham or Atlanta, over 100 miles either one.....hard for me to trust a backyard mechanic....although I could probably wrench this if I can get the harmonic balancer bolt out.....

Any help appreciated!!!!

Tom near Anniston, AL

 

[Peewee]

Yeah, start with pulling the covers off.
If it has only slipped one or 2 teeth, the valves should be ok.
I don't know how many teeth are safe to jump though,

 

[uzz32pete]

A socket and a bar that hits the ground or an empty battery tray with a rag wrapped around it will hold the bolt head while you hit the starter - it will come off straight away.
A 12 volt impact wheel nut gun will do the trick too - and tighten it afterwards. They are cheap nowadays.

 

[JBrady]

This is a strange one. I find it hard to imagine the belt jumping. What would cause that to happen? Maybe an idler/tensioner failure would but if that happened I would think the car would have made noises prior to failure and not run at all post failure. If the belt broke the engine would not run period. The belt makes a pretty good wrap around the drive cogs so it would have to lose teeth or get very loose to jump.

Obviously you have a problem. How many miles on the car? Ever overheated? Was the noise like multiple lifters/valves or one/two? Loud knocking like metal to metal contact or medium clacking like a bad lifter(s)?

Obviously diagnosing an unusual failure on the forum is hard. Give us as much detail as you can. Possible problems include some type of timing belt issue. Oil to cam restriction resulting in failure of cam driven components. Broken valve with valve head in cylinder. Piston failure with broken piston pieces rattling in cylinder. Some type of accessory drive/driven failure. Harmonic balancer failure. Starter drive failure. Internal engine failure.

Any other ideas group?

I am unaware of any of the above being reported in this engine. That said, mechanical failure can occur to ANY engine.

Please keep us posted on your results.

 

[Lexuslvr]

More details on the failure....

The car had been sitting for a day after wife moved it out of garage and back in. I started it and it sounded like an old Chevy engine with loud lifters. I shut it off quickly, checked the oil (fresh change and fine) and then tried starting it up. It cranked hard (like the old Chevy engine where the distributor was dropped in a tooth off....advanced timing) and I gave up and decided to look into the cause.....before risking damaging it further.

Using Supertech oil filter out of necessity where I had always used AC PF53s....it occurred to me maybe the oil filter failed, but that probably isn't it either.

I purchased this car from a friend at 44,000 miles...and it was regularly serviced prior to and after he bought it as a Lexus certified vehicle at 35,000 miles.

Not much to add otherwise...no unusual noises previously, ran perfectly....synthetic oil used...Castrol 10w30.

Any comments apprecaited......can I see enough cam belt to determine failure if I open up front covers without further disassembly?

Any good mechanics in the Anniston, AL area? (between Birmingham, AL and Atlanta, GA)

 

[Lextreme II]

Usually the belt doesnt jump unless, its broken or the tensioner is not working. If your timing belt breaks, then it would not be a good seen. 98 and above have interference engine.

 

[Toymanf]

The situation you describe is very likely to be a soft carbon build-up that is holding the valves slightly open. This was caused by the multiple cold starts with no warm up. This will also cause the ticking noise. It will also cause a strange cranking due to low/uneven compression.

There are 2 ways to deal with it.
1st is to hold the throttle wide open when cranking. It may take about 15-25 seconds of cranking, but you should hear the engine start to catch after just a few seconds. Be persistant, if I am right about the problem, it will start.

The 2nd is to spray Throttle body cleaner through the throttle plate while cranking the engine over. This method is best left to a professional due to the risk of a backfire etc.

Either way, once the engine is running, you should run a good fuel system cleaner through it to help remove the deposits. For the most part, once the engine is fully warmed up and driven, the problem will go away.

Please report back here if this works for you, or if you need any additional advice.

Frank

 

[Lextreme II]

Its hard to diagnose. Take some videos perhaps we see and hear so we can get more information.

 

[sniper]

you should be able to pull the intake off, then the spark plug cover to get a view of the timing belt. In anycase, yes, take some covers off so you can at least get some view of the belt and go from there.

 

[Pagong]

Have you guys heard of the product called Engine Restorer?

I used it in my Subarus (2 of them) and a Dodge Caravan ( had a loud ticking sound
when I drive).

The Caravan saw the most improvement, it stopped the ticking sound and took away the burnt oil smell. On the Subies, they are running better than before.

My question is, is it safe to put these kind of additives in the 1UZ? Or is the engine picky about these things?

I want to try it out on my LS, which has a slight "ticking" noise when idling.

 

[Lexuslvr]

98 LS400 running again

After pulling the RH cam cover and turning the crank I determined there was NO damage to the belt and the timing was right on.

I took Toymanf's advice and held my foot to the floor and cranked the starter for 10-15 seconds and....bingo...car started right up.....and RUNS PERFECTLY!

Toymanf....your diagnosis was RIGHT ON!

MANY THANKS to all that helped me on this issue.....being in the middle of nowhere with nearest qualified shop 100 miles away, this could have been much more difficult.

Next project-change plugs!

Tom

 

[Lexuslvr]

It purrs....

Pretty easy to change plugs on the 98.....the old ones looked fine and could've gone another 30,000 or so, I would guess....

Car runs great......scared the hell out of me, though!

T