How To Mount Timing Belts On A 1991 Ls400

[z_johnq]

Hi,

Long time no talk. Hope all you guys are doing well.

I'm almost half-way replacing my water pump and timing belt (might not be necessary) on my 91 LS400 (with about 160k miles). The water pump is the major culprit.

The problem that I have is I have difficulty of mounting the replaced timing belt. I started from the crank pulley, matching the mark (CR) on the belt with the dot on the pulley; then proceeded all the way up. It looks like it's too tight to mount the belt over the right (passenger side) cam pulley. I turned the pulley clockwise slightly but afraid it might ruin the match between the mark on the pulley and that on the engine. As you tried to take the belt off, fine. Because you could turn it counter-clock to make it match again. But as you mount the belt, you cannot turn it back because the belt will turn too; so will be the crank pulley...

I followed what's at http://www.lexls.com/tutorials/engine/timingbelt.html. It sounds quite easy but not for me.

Any recommendations?

Thanks in advance.

Btw, as I took off the fan bracket, it wasn't so easy as what lexls says either. There are 2 bolt that hold the AC compressor to the bracket. They must be turned loose too before you could remove the bracket; another problem was with the water inlet housing. A few taps will not help much. The part on my car was as stable as a rock. I used vinegar to spray over the neck and it helped.

[landar]

It is a tight fit but you sound like you are doing it correctly. I put a wrench on the LH cam bolt and put counter-clockwise tension on the belt which puts slack into the other side (which is the RH cam that you are trying to thread). Then you can slip it onto the cam teeth. It does take some patience and retrying but keep at it and you will get it done.

[lextechrob]

Double check everything as there are setting marks on the cam and TDC marks on the cam gears. if those marks are mixed up, the engine will be ruined during cranking before it ever start (much worse then bent valves). turn engine over by hand clock wise when belt and lower cover/ crank pulley is on. should only have resistance of compression, no hard stop.

[landar]

You know, I am not sure if he has a '91 (as the title says) or a '95 (as his profile says). If it truly is a '91 then there is no danger of ruining the valves. A '95 is another story.

[z_johnq]

Thanks folks, you guys are great!

Yes, 91's engine is sort of non-interference but 95 is not. Btw, I have both. The 95 broke down too: the EGR pipe that goes to the exhaust got a crack. Someone says you have to drop the tranny to have access to the pipe. I'm still working on it. Almost took me a week to remove the RHS converter because it was very hard to break the bolts. If I knew it was that hard, I'd use oxy-acetylene to burn it off. Anyway, it's a diff. story.

In fact, I like the 91 better because it gives me fewer problems than the 95 does. At least the EGR pipe on my 91 is still OK, maybe a different design (about 165k miles); the 95 has about 110k miles on it. Almost all the lights inside the 95 are gone: the reading lights, the courtesy lights; the strong-arms that supports the trunk lid are broken too. I bought the parts from Amazon but not easy to replace since you have to take off quite some felt before you can access the strong-arms...

I mounted the TB a couple of days ago. But after a couple of spins of the crank-pulley, the TDC was kind of off. That's why I took it off. Last night I tried it again. It was better this time. Since it was so hard to mount the belt on the right cam timing pulley, I mounted the TB on the pulley first (matching the marks on the TB and pulley) leaving the TB off the 1st idler pulley; then used a flat screwdriver to pry it up onto the pulley. I found it much easier than mount it on the right cam pulley. Also, I had some slack on the idler side so that's for the tensioner to set in. It might not be a decent way of doing it. But I can't just mount it on the cam pulley. The TB is on but it feels quite tight. I will have to lubricate the water pump bearing with some coolant before turning the crank pulley. Or it might ruin the water pump.

Thanks again for replying and talk to you guys later.

[landar]

It takes patience to get the belt on correctly, thats for sure. It is normal to be quite tight w/o the tension and you do not have to worry about lubricating the water pump just to turn the crank pulley. It will be fine.

[z_johnq]

Thanks landar for the tip. I think I did it right this time. After mounted the TB, I installed the TB guide and cover, and the crank pulley as well. Make a few turns. The 3 marks matching correctly (2 for the cam pulleys and 1 at the TDC). Btw, I heard someone said about the "u" mark on the timing sprocket means almost nothing. But I used it as my reference of TDC position since it's at exactly 12:00 at TDC, without the crank pulley installed.

Let me ask you something. What's the minimum installation that I have for testing if the pump holds water and timing too? I am just trying to take a short cut, if any, to test my work, instead of completing the installation, then spot something wrong, so have to dismantle almost everything and start over again. What about just having fan bracket and distributor installed; leaving the rest out for some 10 mins, after start the engine? Is that doable?

Thanks again.

[landar]

I am not sure I understand your comment about timing marks but I would be careful using this 'u' mark. Seems to me that cam marks are slightly CW of 12 o'clock. You could be off by a tooth or two and the engine might run but not correctly.

As far as putting it partially together and starting, that would be ok as long as you can get all of the connectors back on, caps, rotors, wires,etc. You may not know if you have a coolant leak until you let the engine warm up fully. I do not think you will save a whole lot of time as the engine will need to be mostly together to run anyway. You are only saving a few plastic covers and maybe the air filter plumbing.

[z_johnq]

Sorry I did not make myself fully understood. For testing, I turned the crank timing sprocket (without crank pulley installed) to see if the other 2 timing marks on the cam pulleys matching the marks on the engine (about 11 o'clock on the left and 1 o'clock on the right); as they matched, I noticed the "u" mark was at 12 o'clock and the "0" mark on the timing cover pointing to the mark (the little "v" shape slot) on the crank pulley installed, which means TDC. Hope I'm right.

Let's see how the engine runs. I agree with you that it doesn't make much sense if I do partial installation, just for save some sweat if start over again.

Thanks again for the tips, and have a good one.

[z_johnq]

Thanks again for all you guys' help. Now the car is running smoothly. It looks everything OK to me. I've put about 300 miles on it since the replacement and there is no leaking around the water pump so far. Hopefully it will last.

One more question. Not sure about the thermostat position is right or not. Is it going to be horizontal by the little bracket that holds the center valve, or vertical? It doesn't look like it makes any difference.

Thanks in advance.

[landar]

There is a 'jiggle' valve on the thermostat that I believe is supposed to be pointed up. But if you have the engine running well and no heating issues, I would just leave it as is. Glad to hear you have been successful with the T belt change.

[LSPaul]

I got to do this very project over the weekend on my own while out of town; thankfully I was near a buddy's house in the city where the water pump failed on Friday night, while on the Interstate. This was NOT how I expected nor wanted to spend my Friday night/Saturday/Saturday night in Madison, WI. I'm thankful I had a full set of tools on board, and was able to find a full TB/water pump kit to purchase locally on a Saturday morning (plus distributor rotors, serp belt idlers and Toyota-spec coolant Saturday evening).

What worked for me when it came time to mount the timing belt, was to have the TB tensioner idler off, mount the belt, then install the tensioner idler pulley, then the new tensioner with pull pin in place. Once I deployed the tensioner, I made sure that the idler bracket/pulley swung up into place, getting things tensioned properly... It took time to figure out this part of reassembly, as the tensioner idler arm/pulley didn't swing up upon deploying the tensioner. Thankfully the cams and crank all stayed in time, even though the belt was on the loose side.

Landar's advice to ignore the lines on the new timing belt after running the engine around by hand to make sure that the cams and crank stayed in time when the crank was at TDC was incredibly helpful, as was his tip of the big Allen key in the hole in the flywheel. I would have fretted much, much more, otherwise--even more than I had all weekend getting the car back up and running, a couple hundred miles from home, plus needed to be 300+ miles away yesterday to meet with clients. Thankfully everything worked properly, immediately: the car started on the first spin of the key at 3 a.m. Sunday morning.

Paul

[landar]

Wow, what a story Paul. Glad to hear that you got everything working again. Changing the belt and pump while on the road is like a baptism by fire. I really like your idea of leaving the tensioner pulley off for extra play while threading the belt. I will have to try that the next time I do a timing belt job. Thanks for posting your story!

[z_johnq]

Hi landar,

There is no valve like that in my thermostat. It's not a original thermostat. I replaced it a few years ago. Anyway, I'll take your advice and don't do anything and keep an eye on the dashboard.

The next project is to replace my 95 LS400's lower EGR pipe, which is definitely a PITA job. I think I can say that I'm almost half way there but so reluctant to proceed. The right converter has been off; 2 out of 4 bolts are out (the lower ones); but the upper ones are still there. I am planning to remove part of the intake manifold to get access to those bolts since it's too far to reach from under the car.

I'll keep you posted.

Thanks again for your help. I like Paul's story too.

Take care folks.