Howdy Folks.
I need some help on finding a loud tapping/light knocking sound coming from my newly purchased 1998 4Runner for my soon to be, first time driver, son. A little back ground on me, I am a former automotive tech with lots of skill's (or so I thought), lots of tools and a shop at my house.
I bought this REALLY clean 1998 4Runner with 178,000 miles cheap from a used car lot becuse of this engine noise. The car runs great with good power, no mis fires and it did NOT overheat on the 30 mile drive home. I have no service history on the vehicle other than a sticker under the hood indicating that the timing belt was changed about 6 months and 5,000 miles ago and a super clean motor on the inside, more on that later.
The noise doesn't start until the engine has been running for a few minutes. The noise is a very loud ticking, nearly on the verg of being a knocking sound. It sounds like its coming from towards the rear of the engine about in the middle or a little towars the drivers side. It sounds like its coming from above the rods and below the valve train. I Know, its weird. The noise completely goes away at 1,000 rpms if I put it in gear and load the engine. In neutral if I raise the rpm's the noise is still there, but a lot less.
In the last two days of owning this thing, this is what I've done thus far, in this order.
1. I pulled the oil pan, screen and windage tray. All 6 rod bearings were tight in every direction. I pulled one rod cap and both the bearing and journal looked great. The crank thrust looked good. No obvious signs of problems. There were only 6 flakes of metal in the bottom of the pan and no sluge or signs of abuse or neglect.
2. I inspected 360 degrees of the flex plate and seen no visable signs of cracking, from what I could see.
3. I pulled both valve covers and measured the valve clearance on all 24 valves. All valves were within spec. All cam lobes looked great as did all gears. No obvious signs of problems.
4. I made sure the timing belt was timed correctly.
5. I changed the oil and filter to 10W-30. I cut the filter open and found another 6 flakes of metal in the filter media.
6. I put the engine back together.
The only thing left to inspect is the pistons, wrist pins, small end of the rod and rings. I know this series of engine can be a little noisey, this single tick is more than that.
Does anyone have any ideas on what to check before I pull the thing out and blast it apart?
Is there any guru's that you know of on this series motor whom I could ask their opinion?
I could get a used engine and install it, but this engine (and vehicle) is SOOOO clean inside and out and well taken care of that I hate to replace it. If used is the way to got, where is the best place to buiy used?
Thank You in advance for your help
Randy
ntoracn@yahoo.com
Riverside, Calif.
I need some help on finding a loud tapping/light knocking sound coming from my newly purchased 1998 4Runner for my soon to be, first time driver, son. A little back ground on me, I am a former automotive tech with lots of skill's (or so I thought), lots of tools and a shop at my house.
I bought this REALLY clean 1998 4Runner with 178,000 miles cheap from a used car lot becuse of this engine noise. The car runs great with good power, no mis fires and it did NOT overheat on the 30 mile drive home. I have no service history on the vehicle other than a sticker under the hood indicating that the timing belt was changed about 6 months and 5,000 miles ago and a super clean motor on the inside, more on that later.
The noise doesn't start until the engine has been running for a few minutes. The noise is a very loud ticking, nearly on the verg of being a knocking sound. It sounds like its coming from towards the rear of the engine about in the middle or a little towars the drivers side. It sounds like its coming from above the rods and below the valve train. I Know, its weird. The noise completely goes away at 1,000 rpms if I put it in gear and load the engine. In neutral if I raise the rpm's the noise is still there, but a lot less.
In the last two days of owning this thing, this is what I've done thus far, in this order.
1. I pulled the oil pan, screen and windage tray. All 6 rod bearings were tight in every direction. I pulled one rod cap and both the bearing and journal looked great. The crank thrust looked good. No obvious signs of problems. There were only 6 flakes of metal in the bottom of the pan and no sluge or signs of abuse or neglect.
2. I inspected 360 degrees of the flex plate and seen no visable signs of cracking, from what I could see.
3. I pulled both valve covers and measured the valve clearance on all 24 valves. All valves were within spec. All cam lobes looked great as did all gears. No obvious signs of problems.
4. I made sure the timing belt was timed correctly.
5. I changed the oil and filter to 10W-30. I cut the filter open and found another 6 flakes of metal in the filter media.
6. I put the engine back together.
The only thing left to inspect is the pistons, wrist pins, small end of the rod and rings. I know this series of engine can be a little noisey, this single tick is more than that.
Does anyone have any ideas on what to check before I pull the thing out and blast it apart?
Is there any guru's that you know of on this series motor whom I could ask their opinion?
I could get a used engine and install it, but this engine (and vehicle) is SOOOO clean inside and out and well taken care of that I hate to replace it. If used is the way to got, where is the best place to buiy used?
Thank You in advance for your help
Randy
ntoracn@yahoo.com
Riverside, Calif.
wondering which way the thrust is and how does that change what ...
