Stump

I finally got my truck back after having the engine rebuilt. I picked it up Monday evening from the shop and have been driving it since. I've been easy on it, just like the guy at the shop said to be. Now when I picked it up, he told me the knock sensor was bad and I would need to replace it. No problem, I can do that.

Well, Tuesday as I was coming home from work I heard an odd sound while I was accelerating away from a stoplight. It was sort of a quick thumping sound that went away. I told the guy at the shop about it and he said to let him know if it happened again. It hasn't. I also told him the truck hesitates when I'm at a stop and I give it the gas to get going. He said that was because of the knock sensor. I'm not sure I believe that.

40 minutes ago, I pulled out of my driveway and headed up the street to the gas station. The engine started making a slapping/knocking sound that concerned me, so I immediately pulled over. I had traveled maybe a quarter of a mile. I popped the hood and as I was looking at the engine it began to idle slower and slower. I manually gave it some gas by hitting the throttle with my thumb and it made the same nasty sound. When I let go of the gas, it idled slower and slower until it died. Probably less than a minute. The bad sound speeds up and slows down as I give more or less gas. I got it started up again and drove back home at about 10 miles an hour. Just enough to keep it from dying but not enough that I heard the sound it is now making.

Once I got it home, it died as I was pulling into the carport.

I can start it, but when I try to get to the front of it to manually give it gas like I did earlier, it dies before I can reach the throttle.

HELP!!

This can't be happening. I just spent $3500 to get the thing rebuilt. Will a bad knock sensor cause this? I know the guy is going to say something about it when I call him tomorrow, but how in the world would a bad knock sensor cause anything like this? I'm skeptical to believe it would. Any ideas what might be the trouble now?

DudeBud

i dont think thats the knock sensor i hate to tell you this but i hope who ever built the motor primed the oil pump before it was fired if not your berrings are toast. how is the oil pressure you may want to get a mecanical gauge hooked you and see what its running at.

miket223

The knock sensor is a common problem to run into on a 3VZ overhaul. Replacing the pigtail wire and sensor is your best bet to make sure the overhaul is going to be a success. If the sensor is indeed bad then the engine won't run right. Usually it'll run like a total dog, moreso than then 3vz already is. It'll be running in a limp mode where the ignition timing is significantly retarted to prevent knocking. I haven't heard of your exact symptoms occuring as a result of a bad knock sensor, but I can assure you that the engine won't be running right without a functional one. You'll need to remove the intake manifold to get to the knock sensor, it's going to be a bitch! I would start by getting the sensor/wire replaced and then setting the ignition timing/idle speed. If the engine had assembly lube on the bearings then it should be fine without priming the oil pump. I still like to crank the engine over with the spark plugs out until I register oil pressure.

DudeBud

hmm the first motor I built just a stock 289 I was younger and thought I new what I was doing well I did not prime the pump and the assembly lube did not do much to help the bearings much. the motor fired and ran fine for a few miles then lost most of the oil pressure. pulled the pan and the bearrings had most of the babit rolled off of them silly me should of primed the pump oh well you live and you learn. Stump are you getting any codes check engine light?

TRunner

When it stalls and you start it back up does it smell rich? If so then it may just be the knock sensor retarding the engine too much. But the sounds that you spoke of seem a bit harsh for a knock sensor problem.

I have some questions though:

What oil did you use?

Did you or the mechanic ever seat the rings?

What is your oil pressure like? (on the gauge in your truck)

Can you do a compression test? (if not I may be able to run out there Saturday and do that for ya)

Steveh29

I've got to question the rebuilder as he didn't put in a new knock sensor and wire while the intake was off. That seems kind of silly to be in there and not do it. Especially since he stated it was bad when you got your truck back.

Colemanfu

Any chance of upgrading to a new runner? My old rig was falling appart - new motor, rear end, the last straw was the tranny going. I could put down 2 grand to fix it or use that $, trade it in and some savings for a new ride. Not trying to knock you rig or offend just shairing my experience. Good luck.

Stump

Everything on the guages looked normal. Oil pressure and temperature were the same. I didn't lose any fluids either. The engine had been running smoothly except for the hesitation I mentioned at acceleration from a standstill. So I don't know that the sensor is really bad. Maybe just the sensor wire? Anyway, it had a check engine light when I picked it up from the shop. The guy told me then it was the knock sensor, and I was planning on replacing it tomorrow.

Ted:

Right now it has 10W30, regular motor oil in it. I asked the mechanic to use synthetic and he told me it would be OK to switch to that after 4500 miles. He said to run regular oil for the first 500 miles, then do a complete oil change, and then change the oil to synthetic after another 4000 miles. He said he preferred the regular oil in order to properly condition the rings. I've only driven 100 miles since picking it up, so I guess you can say I'm in the process of seating the rings. The oil pressure guage looked normal when I was driving it last night. Nothing out of the ordinary.

The truck is at the shop right now. I had them tow it back this morning so they could look at it. I just called the guy and he said he would call me back in a little bit with a status. I can only assume he will do a compression test there.

Steve:

Apparently, the mechanic didn't know about the knock sensor issue until the engine was back together and started up. Then it threw the CEL and the knock sensor code. He wanted $175 for the sensor and 3 hours labor at $68 an hour to put it in. That's why I told him I would take care of it myself.

Colemanfu:

I hear what you're saying. I've already spent more than $4000 when you add in towing and rental car to the rebuild. My truck is paid off, so I would rather not get rid of it and take a car payment for the next 4-5 years. But, trust me, I've thought long and hard about the new ride option.

I'll post an update as soon as I hear from the shop.

TRunner

Very common misconception of anyone a month older then me, it seems. I heard that a lot when I wanted to put Mobil 1 in mine right off the bat. Then I spoke with some folks at Mobil 1 and they pointed out to me that all new engines built by people who care for their engines start it off with synthetic and never put dyno stuff in it. Mine worked great that way, too.

Actually, I would go ahead and switch over to the synthetic after the first 500 miles, then run that for only 2000 miles. Do another complete oil change and then you should be OK to change it every 5000 miles. (Check oil threads for all the arguments form there on out.)

Actually there is a running process you should do to get them to seat. If the mechanic did not do this, then you should as soon as you get it back as it will only start getting oil into your plugs and cause them not to fire. The process goes something like:

Get your truck up to 20-30 mph.
Floor it until you hit 50-55 mph.
Coast back to 20-30 mph.
Floor it again to 50-55 mph.

I think you have to do that about 8-10 times in a row. Don't quote me on it right now, I will let you know exactly how it is done later as I don't have that right in front of me...

Let me know what the shop finds out, though. This should be interesting. They could have left a tool in there that finally broke lose... You never know!

DudeBud

I have been building motors since I was 13 and have never heard anything about this sounds funny to me.

TRunner

Straight out of the Haynes repair manual page 2C-27 Section 25:

Step 7:
Drive the vehicle to an area with minimum traffic, accelerate at full throttle from 30 to 50 mph, then allow the vehicle to slow to 30 mph with the throttle closed. Repeat the procedure 10 or 12 times. This will load the piston rings and cause them to seat properly against the cylinder walls. Check again for oil and coolant leaks.

Attn: Kevin
Step 8:
Drive the vehicle gently for the first 500 miles (NO SUSTAINED HIGH SPEEDS) and keep a costant check on the oil level. It is not unusual for an engine to use oil during the berak-in period.

Step 9:
At approximately 500 to 600 miles, change the oil and filter.

Step 10:
For the next few hunderd miles, drive the vehicle normally. Don't pamper it or abuse it.

Step 11:
After 2000 miles, change the oil and filter again and concider the engine fully broken in.

getitdone

Progress?

Stump

The shop picked up the truck Friday morning and towed it back in. Apparently, they didn't do any work on it that day. When I went to the shop after work that evening to pick up a loaner car, the mechanic said that they would have to start tearing the engine down to find the problem as it is something internal. He said it might be a dropped valve. I spoke to him a few minutes ago and he said they didn't work on it yesterday either because he's "had so many people out of pocket". Umm, okay. Anyway, he said he should know something in the next hour or so and would give me a call back. I'm not holding my breath for that considering this is all warranty work that I don't have to pay for. I have a feeling they are going to take their sweet time getting around to it.

I'll post again when I know more.

TRunner

At least you have afree loner car to put miles on!

By now are wishing you would have used William and me?

We would have had it back to you by now with a lot less stress and probably a couple free beers for ya! That's ok... you live and learn right? I have always learned that the minute you NEED IT DONE NOW is when the poo hits the fan. Also, going with the low bidder will leave you broke. But hindight is 20-20 and all... I'm just giving you a hard time now. You can smack me anytime you'd like.

Give me a call tonight sometime.

Steveh29

At least you can get the knock sensor and wire replaced with no labor charges since he's tearing the engine down again.

Stump

OK, Ted. Here's your smack.

SMACCKKKK!!!!

Yes, I wish I could have used you and William to get this done. This has just turned into too much of a hassle.


Well, I finally got the truck back last Friday. The problem was a broken valve spring. It was covered under warranty and was just a freak thing that happened. No telling why it happened in the first 100 miles after having the engine rebuilt.

But since it was a valve spring, they didn't have to completely tear into the engine which means no replacement of the knock sensor and wire. I will still have to do that one myself.

The loaner car was a POS but at least I didn't have to rent a car for another week.


So I'm picking up a new knock sensor wire today and will replace it tonight. Hopefully it's just a bad wire and not a completely bad sensor. I'll just have to wait and see.

YotaJunky

Stump, you're one lucky guy ( no sarcasm intended ). As you had said, it could have been a much longer wait since they already got their money. Hope you have a smooth ride from here on in.

Good luck!

Troy

Stump

Well, I worked on the knock sensor wire this weekend and found out the sensor isn't bad after all. After taking off the plenum and looking at the knock sensor wire, one of the connecting wires had been pulled out of the plastic housing. So it wasn't making it's connection to the wiring harness. There are two wires coming from the sensor, a brown one and a black one, and the black one had been pulled out. So I inserted the black one back into the housing and snugged it all the way in. Looking at it from the connector side, I could then see it was in place as it should be. I connected it back to the wiring harness, then put the plenum back in place, and hooked everything back up. I started the truck, it fired right up with no hesitation or sluggishness, and I haven't had a CEL since. Go figure.

Really gotta hand it to the mechanic and his shop. Yeah, bad knock sensor my azz. More like shoddy workmanship on his part.

But I've got my truck back, it's running great, and now I just have to take it easy on it until the engine finally breaks in.

THE SAGA OF THE ENGINE REBUILD IS OVER!!!!


and there was much celebration throughout the land........

TRunner

Glad to hear you have yours back... I'm still waiting on getting my truck back together after my whole drive shaft ordeal. BTW - you greased your u-joints lately?

Side note: I just signed a contract to do all IT and networking for a local charter school. If I have some overflow, would you be interested and what kind of help could you contribute?

Stump

Ahh, the driveshaft! Good luck with that. And no, I haven't greased my U-joints lately. We'll have to talk about that one.


Check your PMs about the IT stuff.