Toyota Nation Forum banner
1 - 2 of 2 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
I am real new to the forums. I have a 1mz-fe [vvti] with a wiped cam bearing on the #1 exhaust cam bearing. The #2 bearing cap is also slightly wiped, but not near as bad as #1. This is the left bank [front head]. The bearing journal has lost a solid .010 and the aluminum under the cam is melted. The symptom was an oil leak out the cam seal. 157K miles.

I went to the local U-Pick-It and purchased a new head. In the process of scouting a good head, I found a 97 Lexus with a cam broken in two at the #2 exhaust bearing cap [left bank], and a 2000 Avalon with a cam broken in two pieces at the #1 exhaust bearing cap [left bank]. On ebay, left bank heads are scarce, while right bank heads are plentiful.

I have seen hundreds of engines at the salvage yard, but never a cam broken in half except on these 1mz-fe engines. I have soured the internet looking for someone who might know why, but found nothing.

The local machine shop said it was the result of oil starvation to those bearings. I need to know why. Have I got a bad oil pump? Has anyone encountered this problem. I cannot go to time and expense of installing a new head just to wipe out the bearings again. I HAVE NOT checked oil pressure yet [the engine is still apart] and the machine shop, whose owner is a Vietnam vet and a friend, suggested I check the pickup tube screen to see if it was sludged up. There is not a low oil pressure light.

The head is clean and not sludged up. The oil has been changed every 3000-4000 miles.
 

·
Registered
Joined
·
3,874 Posts
By wiped, do you mean scored, to the point where the oil clearnce between the cap and the cam journal is way beyond target? If so, this does sound of oil starvation. I'm not aware of anything in particular on 1MZ-FE engines like what you describe though.

What exactly is the oil product you use (Brand/weight, etc.)? What brand & type of oil filter do you use? What is the action of the oil pressure light in the instrument cluster?

If you have a problem with a cam bearing now, I question if you don't have problems with the other head as well, and with the rod bearings. Excessive cam bearing clearance tends to starve oil to other bearings because there is no pressure at the cam bearings anymore, so much of the oil flow goes there. Also, it seems strange that you would have have had a VVTi position sensor DTC happen because of this, triggering a check engine light.

Could you provide feedback on all this?

PS: Are you the original owner? If not, and if you use a high detergent synthetic oil now, you may have cleared away some or most of the residual sludge from the head, but if your engine once had a sludge issue, it doesn't mean you are clean below (in the pan, and especially at your pickup screen). Typically, once you see a flicker on the oil pressure warning light, things are pretty bad alraedy. Too bad you didn't put an oil pressure gauge on before you took the engine apart to see what that was telling you.
 
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top