SideStep
New Member
- Joined
- July 28, 2020
- Messages
- 9
- Reaction score
- 1
- City, State
- Alameda, CA
- Year, Model & Trim Level
- 2001 Ranger XLT
Hi Guys!
I've been trying to figure out a rattle that I can best isolate to the lower rear of the 4.0 SOHC engine. Let me go through the history and details.
It's a 2001 Ranger 4x4. The engine got toasted. I tore it apart to rebuild. Mostly everything was new or rebuilt on that 4.0. The deck of the block was milled .004. The main bore was align honed. The heads are a rebuilt set. I used a cloyes timing set. This motor did not have the balance shaft. I used a mellings oil pump and pick up.
When I pieced everything back together, it sounded great. No noises, no issues. After a few 100 miles during break in, I started hearing a slight rattle coming from the lower rear of the engine. I used a stethoscope to listen for the noise. I switched out tensioners and no difference. The noise appears when the engine starts to warm up.
I've removed the serpentine belt started the engine. The rattle still appears.
I've removed the exhaust and started the engine. The thought was to see if the noise may have been the cats. It was so loud I couldn't tell and the engine would not idle. I'd say that was a waste of time and don't recommend anyone try that. I was desperate. Besides, I used my stethoscope to listen for the noise at the cats and the noise wasn't there.
I thought there may be a slight chance it could be the flex plate or torque converter. At 3000 miles on that engine, the transmission goes bad. I get that rebuilt. It came with a rebuilt torque converter. I replaced the flex plate. Still rattles as it warms up.
Since I had the transmission out, I decided to remove the rear timing chain. At 3000 miles, I'd say it had excessive wear on the plastic guides. So I replaced that again.
I tried 10-40 wt oil and 50 wt oil. No difference.
I installed a mechanical gauge at the stock oil sensor location and at the right rear of the block. At cold start up, both read 60 psi. after about 1 1/2 minutes, I start to hear the slight rattle. Cold start fast idle is about 1100 rpm. As the engine warms a bit more, the rattle gets louder. About 45psi. There's only a slight difference of 2-6psi between the gauges. When I bring the rpm up to 1800, the noise goes away. The PSI is about 50-55. After about 15 minutes, idle at 700 rpm, I get 20-22 psi. Bring up rpm to 1800, noise goes away, psi at 46.
The only thing I can figure out is if the rebuilt heads were milled too much and if the cam shaft bore was align honed, It would increase the slack of the chain to the point where the tensioner is of no use?
I noticed both times I installed the rear timing chain that it wasn't quite a smooth easy fit. The gears fit fine and the chain. It was the tension side of the guide that was having an issue. There is a bolt, maybe 8mm, that goes through the top of the head and down to the lower end of the plastic guide. There's a groove at the plastic guide were the tip sits in. Well, It made the guide twist a bit. And made it difficult to install the upper horizontal bolt. The second time I installed that timing cassette, I ground down the bolt about 3/16" so it fit in the groove of the guide.
Any ideas?
I've been trying to figure out a rattle that I can best isolate to the lower rear of the 4.0 SOHC engine. Let me go through the history and details.
It's a 2001 Ranger 4x4. The engine got toasted. I tore it apart to rebuild. Mostly everything was new or rebuilt on that 4.0. The deck of the block was milled .004. The main bore was align honed. The heads are a rebuilt set. I used a cloyes timing set. This motor did not have the balance shaft. I used a mellings oil pump and pick up.
When I pieced everything back together, it sounded great. No noises, no issues. After a few 100 miles during break in, I started hearing a slight rattle coming from the lower rear of the engine. I used a stethoscope to listen for the noise. I switched out tensioners and no difference. The noise appears when the engine starts to warm up.
I've removed the serpentine belt started the engine. The rattle still appears.
I've removed the exhaust and started the engine. The thought was to see if the noise may have been the cats. It was so loud I couldn't tell and the engine would not idle. I'd say that was a waste of time and don't recommend anyone try that. I was desperate. Besides, I used my stethoscope to listen for the noise at the cats and the noise wasn't there.
I thought there may be a slight chance it could be the flex plate or torque converter. At 3000 miles on that engine, the transmission goes bad. I get that rebuilt. It came with a rebuilt torque converter. I replaced the flex plate. Still rattles as it warms up.
Since I had the transmission out, I decided to remove the rear timing chain. At 3000 miles, I'd say it had excessive wear on the plastic guides. So I replaced that again.
I tried 10-40 wt oil and 50 wt oil. No difference.
I installed a mechanical gauge at the stock oil sensor location and at the right rear of the block. At cold start up, both read 60 psi. after about 1 1/2 minutes, I start to hear the slight rattle. Cold start fast idle is about 1100 rpm. As the engine warms a bit more, the rattle gets louder. About 45psi. There's only a slight difference of 2-6psi between the gauges. When I bring the rpm up to 1800, the noise goes away. The PSI is about 50-55. After about 15 minutes, idle at 700 rpm, I get 20-22 psi. Bring up rpm to 1800, noise goes away, psi at 46.
The only thing I can figure out is if the rebuilt heads were milled too much and if the cam shaft bore was align honed, It would increase the slack of the chain to the point where the tensioner is of no use?
I noticed both times I installed the rear timing chain that it wasn't quite a smooth easy fit. The gears fit fine and the chain. It was the tension side of the guide that was having an issue. There is a bolt, maybe 8mm, that goes through the top of the head and down to the lower end of the plastic guide. There's a groove at the plastic guide were the tip sits in. Well, It made the guide twist a bit. And made it difficult to install the upper horizontal bolt. The second time I installed that timing cassette, I ground down the bolt about 3/16" so it fit in the groove of the guide.
Any ideas?
