Real Time Help!!! Engine knock

[99UZJay]

Ok, so I purchased my 80 series back from the guy I sold it to 2 years ago. He only put 20k on it, but I went to pick it up yesterday and on the way home it started to get hot. I stopped and turned on the heat, immediately the temp went down, however it started to knock pretty loud. It sounded to me as if it were on top of the engine, but a friend says it sounds like it was coming from the bottom. We took it to his shop and performed a compression test, Cyl #1 had 120psi, #2 150psi #3 130psi #4 150psi #5 110psi #6 150psi so I guess that was good, we removed the valve cover and all appeared well in that realm, we turned it over with the spark plugs removed and no sound. We replaced the plugs w/o wires, still no noise... We were thinking rod bearing, but we are second guessing now, anyone else with any good options????

 

[D'Animal]

Head gasket blown at #5?

Any water in the oil?

 

[OGBeno]

Well, the 1FZ has two knock sensors on the driver's side of the block that would throw a code if you were indeed knocking (unless, they are not working--they are electrical sensors)....

Are you throwing a knock code?

 

[99UZJay]

no water in oil, CEL light is on, but didn't check the code...

 

[OGBeno]

no water in oil, CEL light is on, but didn't check the code...

There is the first place to start. Get the code (Autozone will read it for free) and report back.

 

[99UZJay]

Thanks, will do

 

[99UZJay]

No knock code, only mass air flow sensor. We are thinking it sounds like is is in the bottom, anyone broke a rod lately? If it is a rod bearing, can that be replaced with the oil pan dropped?

 

[Beowulf]

No knock code, only mass air flow sensor. We are thinking it sounds like is is in the bottom, anyone broke a rod lately? If it is a rod bearing, can that be replaced with the oil pan dropped?

I do not believe we have ever had a report of broken rod on a stock 1FZ-FE engine. That dual turbo drag racing engine broke a rod but he was pushing 900hp. We've heard of melted pistons and bad rod bearings but never a broken rod that I can remember. You can replace the bearings by dropping both oil pans. It is a pretty big job though.

What is the actual Pxxxx OBD-II code?

-B-

 

[landtank]

what are you driving here. No listing for the 80. Dirty MAF sensors can cause missfires. I've seen it twice now. One on my MAF sensor and one on a RX300.

 

[99UZJay]

'95 FZJ-80 205k worked fine 2 years and 20k miles ago. Not normal engnie knock, oil not watered down or milky in appearance. Mechanics stethoscope places the sound under the engine, sounding more like a rod bearing. I am hoping not a rod, but most have me convinced that these empirical findings do not suggest such ie. compression in all 6 cyl's no lag etc.... Any other ideas on what else could cause would be helpful.....

 

[D'Animal]

compression in all 6 cyl's no lag etc.... Any other ideas on what else could cause would be helpful.....

You think these numbers are good?

I think the #110lbs is too low when compaired to the rest.
If the rod bearing is bad, you will have bad compression since the piston is not coming all the way up.

compression test,

Cyl #1 120psi,
Cyl #2 150psi
Cyl #3 130psi
Cyl #4 150psi
Cyl #5 110psi
Cyl #6 150psi

I truely hope I am wrong.

 

[OGBeno]

You can replace the bearings by dropping both oil pans. It is a pretty big job though.

x2. IIRC, Bailey did this from below recently and he mentioned to me that it was indeed awful.....

 

[99UZJay]

Brass shavings small oil pan, most likely rod bearing. Going to try to take the main oil pan off tomorrow, anyone have experience with that??

 

[Beowulf]

Brass shavings small oil pan, most likely rod bearing. Going to try to take the main oil pan off tomorrow, anyone have experience with that??

You have to lift the engine a couple of inches and remove the sway bar and, IIRC, the relay rod. I think a cross-member has to come out too. CrusingGA and CruiserDan have threads on this repair. They were a long time ago and I can't recall the details.

-B-

 

[lacruiser]

Your compression numbers are not good, way too much variation between cylinders, numbers 1 and 5 and quite a bit below the highest, I think the max variation allowed is something like 15% or something.

If you see shavings in the oil pan, obviously one or more of the bearings has toasted, but usually that means the journal has also been scuffed, so you can't get away with simply putting in a set of bearings and expecting it to last any length of time. On the other hand, if one of the bearings is messed up, but the journal looks good and mics within spec, you got lucky, go for new bearings and you'll probably be OK.

If you do remove the pans and the rod bearings all look good, also check the main bearings and thrust washers. I'm not certain, but on this engine the thrust washers may actually be part of one of the the main bearings.

You might want to perform a wet and dry compression test, in order to get a handle on the condition of your rings. Low compression can be caused by other than ring seal problems, especially valves, so you may want to have that info before you yank apart the bottom end. Wet/dry test will tell you a lot, and a leakdown test even more.

 

[Mo Rocks]

This is a LONG shot, but I have seen this happen twice before. Somehow the dipstick gets hit by the crankshaft !!
I would not have believed it if I was not standing there....this was years ago and it was on SBC engines both times....

It is probably not your situation since your engine overheated just before the knocking sound started...and you have some discrepencies in the Comp. readings.

But it is easy to check this one in a million causes....just pull back on the dipstick with the engine running and see if the sound changes or goes away.

Good Luck !!!!!!!!!