Engine knock when it's hot...

[Azca]

Mud Men (and Women ) I noticed this about a month ago. When the air temperature is over 100 and the engine is warm, the engine knocks. I did try higher octane fuel but nothing changed. I do not notice this in the mornings when it is "nice" (below 90) out.

So what do you think??? Is it the knock sensor, timing? WWMMD? (What would Mud Men do?)

 

[95ToyCruiser]

What weight oil do you run? I know the cap says 5w-30, but that's just to get around the stupid us emissions s***... Everywhere else in the world they recommend 15w-40 (if my memory serves correct)...

That's all I run in mine (rottela blue), I'm thinking that your oil is too thin with the high ambient temps... Try adding some Lucas, or better yet, do an oil change with a thicker oil..

 

[94SRUNNER]

Check the timing.

 

[Azca]

What weight oil do you run? I know the cap says 5w-30, but that's just to get around the stupid us emissions s***... Everywhere else in the world they recommend 15w-40 (if my memory serves correct)...

That's all I run in mine (rottela blue), I'm thinking that your oil is too thin with the high ambient temps... Try adding some Lucas, or better yet, do an oil change with a thicker oil..

Running Mobil 1 10-40 as from what I have read the Mobil 1s are on the "thin" side...

 

[Youngjoonni]

Oil weight in itself does not cause you problems. I run 0w-40 Mobil 1 syn with 200k on tbe original engine at 7* advance timing without any issues.

OP should describe exact details as to how they concluded that a knocking issue exists.

If a knock issue does exist, retard timing immediately. Record the inital timing along with how much you removed to resolve the issue. Next step is to figure out why your issue occurred and correct it. At this point, if you are unable to fix it yourself, post up all the details and data and ask for help.

 

[Youngjoonni]

I should mention that I am currently running 0w-40 synthetic for multiple reasons.

I just finished repair all my visible oil leaks and wanted to see if I had any other leaks.
I recently acquired my cruiser and performed a compression test. Even with relatively even numbers indicating minimal wear, I wanted to see if she burned any oil.
I was curious to see if it would increase my mpg.

I don't have enough data for an update as I have only put 2000 miles on my cruiser other than to state that she is a healthy beast.;p

 

[scottryana]

I also run 0-40 Mobil 1 in my truck, because it's what I run in all my other cars. Can't see why it would cause any issues here. I would say check timing and pull the CEL's does it sound like you are knocking? When does it happen? High rpm under load?

 

[JCruse]

Mine knocks a bit too which I think is in the normal range when I run 89 gas or better. But for a while it was knocking really bad all of a sudden and the gas wouldn't help anymore, I found a loose vacuum hose by the EGR valve, pushed it on all the way and that fixed it. Now it's back to it's "normal" knock.

 

[Overland Tailor]

Mine knocks a bit too which I think is in the normal range when I run 89 gas or better. But for a while it was knocking really bad all of a sudden and the gas wouldn't help anymore, I found a loose vacuum hose by the EGR valve, pushed it on all the way and that fixed it. Now it's back to it's "normal" knock.

There is no "Normal Knock".

Something is up.... Maybe mechanical or bad fuel related, but you should find out why and fix it.

Also "89 or better" or 89 or less?? If you are running 92 or 93 and still have audible knock, there are issues.

Best,

J

 

[coax]

Check the timing.

x2. Start with the easy checks first. Could be the dizzy got bumped during some work and if the bolt was just a bit loose that threw off the timing. No telling until you jump two of the pins (FSM would have that) and throw a timing light on there.

 

[LINUS]

I'd be wondering why your knock sensors aren't kicking in & retarding the timing on its' own???

You might try going real octane rich by letting the tank go to near empty, fill with ~7.5 gallons the best fuel you can get, and add a quart toluene they sell in paint sections of major home improvement stores (it's 116 octane, research grade is 120). That full OBD2 rig should be running near constant on the knock sensors if it's as bad as you say, and check your distributor to make sure it's not so far advance the retardation the knock sensors provide isn't able to get you in a proper range.

 

[Michael Hanson]

Hi, I use Mobil one 10-30 syn. No knocks any weather. Try simple stuff like spark plugs. Mike

 

[Azca]

I noticed it when the window was open and accelerating from a stand still. Seems to be most noticeable at low RPMs and "rattles" pretty good until around 2000 RPM.

She is burning oil, about a quart every 3000 miles (has 180k on her). That may drop a bit as I just replaced the gasket on the oil cap but not much oil escapes there. Last code I had was an O2 sensor but that happened after I cleaned the **** out of her chasing down the leaks as part of the base lining of the rig earlier this spring.

 

[Azca]

Oh, I do not hear it when the engine is cool (even if the temp is over 100) or when the engine is hot and temps below 90.

 

[CruiserDave]

Ever find out what was causing this problem?

 

[LFD2037]

I think I have the same issue. Not a 'knock' like he first described but a rattle from take-off to about 2K rpm's when engine is warmed up. Just started since its getting warmer outside (about 80* and hotter).

 

[Azca]

No, went to work it last weekend and couldn't get a timing light. I have a friend who will be dropping me one and will try again this weekend. Perhaps I am OCD but when I say rattles it is not something I can hear in the cab unless I roll down the window and it does seem to quit at about 2k but I am not sure if the engine noise is just drowning it out. Premium fuel does not help, I am good on oil (mobil 10-40 high mileage) and run fuel treatment through it about every 1500-2000 miles. No check engine light and seems to be fine otherwise...

 

[94SRUNNER]

LFD2037...have the timing checked or borrow a timing light and check it yourself. It sounds like that might be your issue.

 

[Azca]

Timing checked it was off a tad but now is correct. Unfortunately it is still knocking, perhaps a little more than it was before. It is certainly not bad but it is there.

Any suggestions? I am thinking of replacing the spark plugs now, anything else I should look into?

 

[CruiserDave]

I've been reading every post on this topic and it seems like no one knows a fix for this problem except to open the motor and clean out the carbon.
From what I've read most just live with it. I'm going to mod my fan clutch and maybe change my radiator in a attempt to keep water temps lower.
Then run some cleaners through the motor add pcv catch can and last add a snorkel to try and lower intake air temps.