Hello everyone I had some recent posts about my low idle and poor mileage. I tried driving my sons 240 and noticed it had a rough idle and no power. I checked the oil and it was above level and smelled of gas. I drained the gas and thought maybe it was a leaking injector as I didn't hear #3 injector clicking using the screwdriver to ear test. I replaced all four injectors, changed the oil and filter. Drove it for a few days the gas mileage continued to be bad maybe 10 miles a gallon and still a very low idle. I decided to install new fuel regulator, engine coolant temp sensor, knock sensor, and temp gauge sensor (I figured I was in that area anyway). I also changed the engine coolant thermostat.

Note the oil did smell a little gas and the dip stick was just a little high. I planned on changing the oil after I cranked it over to see if my recent work changed anything. Well it idles real nice now about 800 rpm but now I had a weird noise that I'm so hoping is not big issues. Car is low on fuel but I wouldn't think this would have anything to do with the noises.

I hope I have not spent hours and hours plus lots of $ restoring this 240 and now the motor is toast.

 

This noise is mechanical, sounding like the dreaded "rod knock; meaning, not related to the things you did.

Does frequency change with the RPMs when you rev it up? Not good... I'd spray some water on the belts just to eliminate them as a possible, if unlikely cause.

What's the history of this motor? Mileage, length of ownership, oil change history, etc? Rod knocks are rare in Volvo b230 but not unheard of. If you do have a rod knock, better just get another used motor. Rebuilding it is cost prohibitive.

 

We have only had this 240 for about a year. Engine has like 180k miles on it. Basically rescued it when I purchased it for $600 as a project for my teenager to drive. Since owned we have changed the oil regularily, full maintenance, new timing belt, cleaned throttle body, new rebuilt injector, new fuel regulator, then the recent work that I posted. Bunch of other stuff like suspension tierods, ball joints, front and rear shocks, tranny mount replaced, fuel filter and replaced with a rebuilt MAF from wrecking yard. Motor sounded very good and drove strong before this rattle sound that I have. It doesnt sound like a low end knock but a rattle like there is a nut flying around in the engine.
I had been troubleshooting the car had been running rich for months. Spark plugs fouled a couple of times and heavy black showing running rich. That is why I had cleaned out the throttle body, replaced house from the MAF, changed MAF, replaced 02 sensor, fuel regulator and the rest. Car was actually running fine at all speeds but had low idle like 500 to 650 range. Then recently getting poor gas mileage it dropped even more after I installed the rebuilt injectors. I then decided to replace the ECT with the other sensors on that side of the block. Now I wish I would have changed the oil again before cranking over and letting it idle for a few minutes.

Did changing the knock sensor cause anything?
I'm wondering if I should change oil and filter maybe add some Lucas additive then fire it up.

This 240 is not perfect but I was on path to make this a reliable ride for my two teenagers to drive for the next 5 years. Plus having a third car to use has been very useful.

 

Well if it is running rich and dumping fuel into the oil, then I wouldn't be driving it until that is corrected. Thinning your oil could cause all kinds of internal damage. I listened to the video and while it doesn't sound good at all, it doesn't sound like rod knock to me. Use a stethoscope and try to locate the general vicinity of the noise. Narrow it down from there.

 

Did you change the oil?
If the oil is excessively thinned out with gas, you'll get the noise you hear!

Change the oil and see if the noise disappears with the new oil. If you get lucky with the noise, diagnose the cause of the rich running, correct it, go from there. Also, take a compression test--the first thing to do in figuring what you got...

 

I really appreciate the feedback.

I have been troubleshooting the fuel issue and had thought the rebuilt injectors solved my problem. Drove the car for about 3 days and noticed major fuel consumption. Checked dipstick found fuel smell again and fluid level about 1/2 to 3/4 of a quarter above the max oil line. I installed the ECT, knock sensor, fuel pressure regulator and coolant thermostat then fired it up for idle and heard the noise. The 240 has not been driven since I found noise.

I will give it an oil and filter change and see what I get. Maybe I should add oil and hand crank it a few times.

 

Adding recent picture when I replaced Valve Cover gasket a few weeks back.

 

thats a lot of sludge and varnish.

 

Well, your oils is thinned out--probably the injectors are leaking. Who rebuilt them? And oil that's too thin will cause the clanking you hear--not even thickness to cushion the bearings... Your camshaft looks OK, what sludge?
Just change the oil and filter, and I bet your noise goes away. But do find the source of the fuel dumping into the crankcase...

 

Have you done a compression test?

 

Oil change done. Mobil 1 Synthetic 5-30 High Mileage and one quart of Lucas Heavy Duty Oil Stabilizer. Note that I typically don't add any additives to my main cars but after the gas in the oil issues and the rattle I felt desperate.

Okay now listen and most of the rattle is gone. I hear a little now and then but I have not drove the car yet and it has only idled for about 3-4 minutes.

Next - Engine Compression test

 

is the heat shield rattling on the exhaust pipe ?

its really hard to tell with recordings, there's no reference for the audio gain.

 

Okay so finally got the compression test done. This is my first time doing this. Free rental tool from Autozone.

Dry test
1cyl - 150
2cyl - 155
3cyl - 153
4cyl - 150

Wet - sprayed two or three squirt down the spark plug hole best I could. Not sure how accurate this is as the first reading I had from cyl 1 was 185.
1cyl - 172
2cyl - 165
3cyl - 160
4cyl - 155

We drove the 240 for about 10 miles up to 60mph and drove perfect. Late in the drive going about 30-35 heard a quick rattle for about 5 seconds then nothing. My son said when it made the sound the rpms dropped a small amount. Then drove home going same speed and car performed well. We did drive up some hills in second and the car pulled the hills very well. Brought the car back and did the above compression test. The plugs did have a lot of black carbon built up on the plugs again. I bet there is a lot carbon built up on this engine.

 

Your compression is fine! I think what you think is "carbon' on the plugs, is actually unburned gas, black sooty deposit? (carbon takes a long time to build up). You have a rich running engine, either leaky injector(s) or the computer is dumping too much gas for some reason...

 

Yes black sooty spark plugs. When I replaced the O2 sensor a month back it was covered in black soot as well. I went ahead and installed a new set of Bosch Cooper Super Plus plugs. Going to check the oil each day for gas smell and plan on checking the plugs next weekend for black soot.

 

Btw, if ALL your plugs are sooty, your problem is not injectors, how can all injectors be equally "leaky"?

Not crucial in this case, but those Bosch Super+ are garbaaage... Use NGK copper, $1.39 ea., you are gonna get much better results overall...

One reason for engine running rich is too much air due to leaks after the MAFS. The computer senses a lot of air, sends corresponding amount of too much fuel which is unburned...

 

That is interesting as I had thought the Bosch Super+ was the recommended plug other than Volvo OEM. I will give the NGK a go. Air leaks?! I will torque everything down again, check hoses and clamps.

On the positive note I do not smell gas on my plugs!

Question - None of my hoses look cracked but hard to tell. The hose from the MAF to the throttle body was pulled from a wrecking yard and looks good but I'm not 100% confident.

 

go over that plastic air pipe with a flashlight in a dark room

small air leaks affect idle and low rpm running more than high rpm.

 

Actually, for many applications Volvo recommends NGK plugs...

 

Drove the car about 5 miles tonight up to 60 mph on highway. Cold start idle with the new plugs has increased to about 800 rpm. After driving and warmed up it now idles about 550 or 600. Pulled oil dip stick for gas smell. Nothing strong but maybe residual - not conclusive. Idle is smooth as it has been in a long time. No rattles / knocks from engine during idle or driving.

It would be nice if I had some kind of an air/fuel ratio gauge on this car. Any other idea on how to know if fuel starts to dump in the oil again other than guessing at the smell of oil from dip stick or oil cap? I don't want to run the risk of the oil getting super thin again. Going to have my son drive it to school and back which is about 2 miles each way. Will check the oil dipstick again tomorrow night for gas smell.

I'm wondering if I should clean up my old MAF and try it out. Clean out the hose from MAF to throttle body again then try the light test that Pierce suggested.