TC noise after engine rebuild

[swapdip]

OK so after my timing belt tentioner bolt snapped on me, I undertook the long and painful process of saving money for a new engine, getting it shipped up here, getting some guys to help me take the old one out, new one in, now everything is all buttoned up but we still have a few issues, perhaps you guys could lend some advice. My truck is a 1990 4x4 auto, and we stuck in a 1995 2wd auto engine, took a little bit of finesse but we got it in. Last week, the truck would start up pretty easily, but not rev very high. Took the front end apart and found the tbelt was off a tooth, ok that got sorted out now it runs better, however we still can't get it above 35mph, it feels like a vacuum leak but we checked real hard for that, found none. The truck still runs very sub par, wants to stall after revving it hard, lopes at idle. The truck runs better the further we twist the distributor, but we have already twisted it much farther than it was in the previous engine. It is the 90 distributor which we are using in the 95 engine. In a few days they are coming back and we are going to try and advance the distributor even more, see if that helps out. However, I was wondering since we had the intake manifold off the 1990 which was in much better condition, we put that on the 95 motor. That includes sensors wiring and all. Are there small differences in the design of the intake manifold or the distributor from 90-95 which might make it run like this? The truck is throwing no codes so I am disinclined to think it is a MAF or TPS or another sensor. Also I should point out that the gas in the tank is about 5 months old, I topped it off with 3 more gallons of fresh gas and about a third of a bottle of octane booster, no steam noted from the exhaust so i dont think there is water in there. Also I know gas loses its potency after a while, but I have run much crankier engines on much older gas before, and I am hesitant to just blame it on bad gas. Gas pressure is good, spark is good and strong.

 

Additionally, there is a knocking coming from the torque converter below 500rpms. It is a hell of a knocking, and we have been hesitant to run it too far while it is doing this, the bolts are tight but maybe there is a bent part of the flex plate banging around down there? We are also going to investigate that. One of the guys thinks that these problems are related but I am not so sure. Do you guys see any flaws in our methodology? We are all three shadetree mechanics and not entirely sure what the problem could be. Advancing the distributor even more might help us out, and I think we are going to open up the torque converter to see what the hell is making all that racket, but I am not very confident in these solution's ability to make the truck run right again. Any advice would be more than appreciated.

 

Thanks

Edited December 6, 2010 by swapdip

[Cuong Nguyen]

Are you positive that that the timing belt is on properly and the distributor is put in correct and wired up in the correct firing order? I don't know about your TC problem. If the flex plate was bent, you would visually notice it right away when you installed it. Plus, the TC bolts up to it.

[swapdip]

Firing order is correct yes, timing belt also correct. I actually made a lot of notes when I did the timing belt last spring, recorded how many teeth need to be between the cam marks and crank mark, so we are good on that. As for the distributor, we have been twisting it around trying to find the right spot, so far we can get it to run "better," but still not great.

 

And yeah I thought it was kind of weird that the flex plate might be rubbing making that clanging sound, but the entire torque converter shifts around when accelerating in neutral, more than it should, which indicated to me that something must be off. Flex plate was just a guess, thats all.

[swapdip]

Any other ideas?

[sewebster]

Well, you should likely be adjusting your timing with a timing light, not just at random... so you are finding that it runs better when advanced, because it increases the idle speed?

 

There are a bunch of diagnostic procedures for unstable idle etc. etc. in the FSM that you could try..

[jj big shoe]

I would think at 500 RPMs your engine is struggling to stay running. Are you sure the knocking isn't related to the engine dieseling and the noise is being transferred thru the low end and that's what you're hearing? Also, when installing the dist you're looking to line up the contact, not the stalk where the plug wire connects, with the rotor. I don't mean to question you and your pals technical abilities, but its a common mistake. I haven't done tons of rebuilds or anything but it really sounds like a timing problem and I know if you quick-step through the dist install and its off a tooth you'll never get it to run right.