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Discussion Starter · #1 ·
I have loud knocks from 1200-2000 RPM, started about 3 months before I pulled the heads and it sat for 2 years until today, I rebuilt the top end, changed lifters, pushrods, gaskets, MAP, Camshaft Position Sensor got it all back together. Idles like a dream, no engine light on. So I carefully drove it around, when I can get it above +2K I had test it and sure enough no knock. When it decompresses slowing down no problem down to idle. Gasing back up throug 1200-2000 its scary at times, I think a rod is going to come through the winsheild. Pisses me off really. I dont like things I cant fix. So, thinking tensioner or idle wheel, I cut the belt to save time and revved away and still the same problem above >1k <2K knocking, the knock varie quite a bit in those ranges, so now I think has to be crank, camshaft bearings or something..
I hate this. Timing Chain? Rod Bearings (I would think it would knock all the time)? Oil Pump? Something in Tansmission like Flex Plate cracked? OBD II shows nothing, no codes, lots of the attributes look good.
Compression is fine on all 6.. frustrating... . Anyone have this problem before that fixed it or is it time to buy another Toyota Sienna? ;-)
 

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Discussion Starter · #2 ·
2005 Chrysler T&C 3.8L - I have loud knocks from 1200-2000 RPM, started about 3 months before I pulled the heads and it sat for 2 years until today, I rebuilt the top end, changed lifters, pushrods, gaskets, MAP, Camshaft Position Sensor got it all back together. Idles like a dream, no engine light on. So I carefully drove it around, when I can get it above +2K I had test it and sure enough no knock38L T&C. When it decompresses slowing down no problem down to idle. Gasing back up throug 1200-2000 its scary at times, I think a rod is going to come through the winsheild. Pisses me off really. I dont like things I cant fix. So, thinking tensioner or idle wheel, I cut the belt to save time and revved away and still the same problem above >1k <2K knocking, the knock varie quite a bit in those ranges, so now I think has to be crank, camshaft bearings or something..
I hate this. Timing Chain? Rod Bearings (I would think it would knock all the time)? Oil Pump? Something in Tansmission like Flex Plate cracked? OBD II shows nothing, no codes, lots of the attributes look good.
Compression is fine on all 6.. frustrating... . Anyone have this problem before that fixed it or is it time to buy another Toyota Sienna? ;-)
 

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Probably a rod bearing starting to go. It's not too difficult on these vans to drop the oil pan and check the rods for play, or even pull rod caps and look at the bearings/journals as long as you get the correct torque specs to put it back together again. There were 2 different types of rods used, and each type has a different torque spec/method. Also, starting in 2005 the 3.8s liked to use oil so maybe it was starved of oil for a while earlier in it's life?

Siennas have their problems too. Have to worry about external oil pipes or hoses cracking/leaking/blowing out, oil pan sludge in the 1st/2nd gen vans, and head gaskets leaking and having to replace the whole cylinder head because they can't be machined.
 

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Discussion Starter · #4 ·
Probably a rod bearing starting to go. It's not too difficult on these vans to drop the oil pan and check the rods for play, or even pull rod caps and look at the bearings/journals as long as you get the correct torque specs to put it back together again. There were 2 different types of rods used, and each type has a different torque spec/method. Also, starting in 2005 the 3.8s liked to use oil so maybe it was starved of oil for a while earlier in it's life?

Siennas have their problems too. Have to worry about external oil pipes or hoses cracking/leaking/blowing out, oil pan sludge in the 1st/2nd gen vans, and head gaskets leaking and having to replace the whole cylinder head because they can't be machined.
Not having a lift andworking under thier in 100+ heat in Sacrmento (the normal for summer). I did have the pan off , new gasket, I looked but not too hard. I guess I was hoping it was all ok, but I did think about it. I have the specs, torque wrench, air impact drivers and the Hanes Manual for source. Can you change journals or bearings from below with removing the camshaft? Might be dumb question I should look that up ;-) Always had oil though. I think there may be phase 2 of this now below and I was thinking about pulling the oil pump, I have gaskets for all of it from the kit except a new pan gasket I can get. I am going replace the belt and idler and tensioner.
I am going to pull in the Seinna, I have new struts,drilled/slotted rotors, pads, Shocks, Door Handles and new mirror on driver side I guess I should check out the oil pan.It runs and has been so good for $3000 used car. 171,000 no leaks. I replaced the whole top end 2 years ago. I am also going to add HHO kit (Hydrogen) to the sienna that taps into the Plenum. I want to add one to the chrysler if I can get it going. THanks fior the info.
 

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I am also going to add HHO kit (Hydrogen) to the sienna that taps into the Plenum. I want to add one to the chrysler if I can get it going.

keep it simple... if you have to ADD a system to the vehicle that wasn't originally there to make it run right, something is very wrong and needs to be addressed

show us a video of the noise, recording from wherever the noise is heard best
 

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No, I haven't installed one.

I haven't installed one of those little magnet doodads that go over your fuel line that are supposed to increase MPG, either.;)
If it's fuel economy that you are seeking your best bet is to install some SplitFire spark plugs.

Instant 20% improvement in mileage and power. Guaranteed. (y)

Audio equipment Material property Battery Electronic device Cylinder
 

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show us a video of the noise, recording from wherever the noise is heard best
NO! No video! A video might make it easier to determine the cause of the noise. I would much rather see this thread go to three or more pages of folks blindly guessing at things that could be the problem before the OP vanishes never to be heard from again. That's the way it usually gets done around here.
 

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My cousin works in a shop with a fleet of vehicles, perhaps 20 or more. One day some salesman shows up selling some add on kit that separates the hydrogen out of water and feeds it to the engine for an increase mileage and all kinds of wonderful things. The management is goes it and buys/installs several of these kits. The result was no discernable change at all except for the loss of time, labor and money.

10 years ago, working on a 3.3 I rotated or held the crank pulley/harmonic balancer by placing a screw driver through a hole in the pulley. Turns out I bent [ put a slight wobble in ] the pulley/balancer. At low rpm the engine made a low pitch thudding noise like bad crank bearings. Luckily I noticed the balancer wobbling perhaps 1/16th of an inch. I replaced the pulley/balancer with a used one I hand on hand and the noise vanished. I guess the pulley, with a little lateral run out, was causing the crank to move back forth using up it's end play.
I would look into this before assuming it's rod bearings
 

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While you have the oil pan off, replace the o-ring that seals between the oil pick-up tube and the block/pump to assure you are not pulling in air as you try to pump oil. You should be able to get a gasket kit that includes this o-ring along with a new oil pan gasket. Doesn't necessarily sound like the source of your problem (caused incessant top-end clatter on mine), but it makes sense to do while you are in there just in case as it can affect proper oiling of the motor...
 

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In my experience with other types of vehicles, restoring the top end and regaining good compression can expose a bottom-end problem. The bearings were already worn but the knock was not so apparent because the compression was lower. That dull knock is the warning that a rod is about to embark on a solo flight. Should be parked and repaired...it's the only way to save it.

Source: Mazda B2000 with a giant hole in the block 😁
 

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Discussion Starter · #17 ·
I cut the belt just to get right ot it and see if it is the idler or Tensioner , nope still knocks. Almost 99.9% sure its rod bearings and the next thing I am after when i get a chance. I took care of the damn headliner dropping isuse and I am not spending $700 like I did ont he caravan to have it redone. I painted that things, colorful, I like it.
Motor vehicle Vehicle Automotive design Head restraint Automotive lighting

Automotive lighting Hood Wood Bumper Textile

Automotive lighting Door Wood Fixture Hood

Product Automotive design Vehicle door Electric blue Service

Automotive lighting Motor vehicle Hood Bumper Automotive mirror
 
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