M20 sounded like a v8, tbelt?

[jw 325ic]

So for the past couple of months my car had been idling funny. I had been changing various hoses and cleaning parts to try to fix the idle or spot where the issue was. But about a week ago I started to hear a sound like a loose pulley of some sort. I assumed it was the water pump or alternator, since the idle would dip low. The sound would go away after it warmed up a bit though..

But then all of a sudden, on Monday of all days, I was sitting at a light, idling fine, but with the little “loose pulley” sound, and take off to turn left. But when I pressed the throttle it sounded like a v8 with its headers cut off… so I pulled into the parking lot across the intersection and shut it off, towed it home, and pushed it in the garage.

Did my timing belt become loose? I am going to tear into it this weekend but does anyone have any ideas? I’ve read that if the engine all of a sudden becomes loud like that that it is a loss of oil pressure. Like I said, ill be looking into it this weekend and can post more updates but so far im thinking rebuild or swap…Thanks in advance



Also, the thermostat had been stuck overcooling the engine with all of the bolts stripped out making it damn hard to get.

[nando]

if your timing belt came loose the car would have died almost immediately. you can run a compression test as a quick check.

[jw 325ic]

Ok, thats good news from 3 days of bad news left and right. Im just afraid to start it til i check the belt and have a peek under the valve cover. Im hoping someone else may have had a situation similar and will chime in at some point. But could fouled spark pkugs cause that or what? Im a bit of an ignition noob... Thanks though nando

Plus i just replaced my struts and put a new top on it...what luck?

[jw 325ic]

update:

felt risky, plus my dad wanted to hear it...so i tried starting it and it started and seemed like it would run, but i turned it off after it ran for a few seconds just in case. so im ruling out timing belt getting snapped...but what about it being loose?

although...my dad thinks it may be exhaust related because of how loud the motor sounded...any more ideas are welcome.

[Syncro325is]

pull the valve cover.

[jw 325ic]

doing that tomorrow afternoon. going to check exhaust also. what else would come loose or go out to cause an i6 to sound like a modded v8?

cat suddenly going?

loss of oil pressure?

what can overcooling damage in the engine?

[Easily Distracted]

Start with some simple tests like check the exhaust over carefully for cracks or missing nuts or carbon where it shouldn't be. You can pull the valve cover and inspect for piece of mind and a compression test can tell you if a valve is already bent. The squeal and the exhaust could be unrelated. The belt sound could be your timing belt tensioner going and maybe causing resistance makiny a lopey idle. I've heard of timing belts jumping a tooth from a bad tensioner or broken guide but if you have good compression you may just need to do a timing belt (along with all the related parts & procedures you should do at the same time) and fix a broken exhaust pipe. Good luck! Hope it's simple.

[jw 325ic]

Ok so the cat snapped clean off the header where it bolts up. Couldnt even see it at all. Only noticed it when i was feeling for a crack and it wobbled. So thats the v8 growl...now for the pulley noise and to check valve clearances..and somehow get that thermo out

[NC325iC]

getting the thermostat out isnt hard, get a bentley manual if you dont have one.

[Easily Distracted]

Don't disregard that squeeling sound though. Especially if it seems to be affecting idle. If its the tensioner the next step could be a broken belt and a ruined head. With these heads, if the belt breaks there is like a 99% chance it will at least bend valves. : P
Not trying to freak you out but I wouldn't want it to bring your project to a sudden end. If the timing belt is due because of either mileage or age, or if you just don't know if the PO ever changed it, put it on your very short list.
That being said, hopefully you just have a stretched belt. Start the car up and when it usually squeels, spray some soapy water on each pulley one by one. If the sound suddenly disappears you may have the culprit.

[Easily Distracted]

Also check the fan for play and see if it wobbles. If it does, your water pump is probably showing wear and may be contributing to the pulley squeeling.
As a rule of thumb, I always try to start with the simple stuff first before really tearing in to things. More than once I have gone and done a big job only to realize it was actually just a simple fix. Sorry for preaching. : )

[jw 325ic]

Its all good man. I actually did my tbelt/tensioner/water pump Nov-2009. Plus i work 10 mins away from my apartment..groc stores 5 away etc..so mileage isnt bad on it (broken odo). Im going to open the valve cover today or tomorrow and check the belt. I have a new icv i want to check also. I still have to figure out why my bros m42 wont start. Its been a hell of a week..

[jw 325ic]

Also my dad bought it in '90 and i took it over in 2003. So i know all the history since ive been working on it since 16 yrs old. My dad had the thermo replaced some 10-12 yrs ago and it just went out 4 mo's ago. I attempted to put a lower temp thermo in when i was 18 and wound up stripping the weak ass allen style bolts the shop put in. I tried to pull the housing and those stripped too! So its gonna be a PITA to get out. Im lookin at ez outs and left hand drill bits : /

I checked the fan/WP for play and its as solid as it was when new, the oil level was fine and still clean (no metal shavings). But yea either this afternoon or tomorrow morning ill be pulling the vc while looking at my bros m42 then getting to my timing belt to inspect all that...

[NC325iC]

i thought the housing was on studs/nuts?

[jw 325ic]

Housing is on bolts which on mine were 6mm allen

EDIT: NC325ic I just looked at realoem and it shows its on studs also. last i remember looking at my thermostat housing, there were flat allen headed bolts holding it on. so maybe the shop that screwed me over on the housing bolts also pulled the studs and fitted bolts. i need to look at mine again to make sure but i could swear mine is on by the same 6 mm allen bolts

I pulled my valve cover, everything is tip top... clean too not a drop of sludge either :)

Mid-4 VC nuts werent even tight so maybe that was my air leak?

Im gonna tear the front of the engine apart tomorrow and check the belt and pulley.