1G 2.0 Laser RS suddenely died

[TylerW]

Hey everyone...

We have a 1990 Laser RS 2.0 non-turbo with 133k miles.

It suddenly died the day before yesterday, and I wanted to get some ideas about what to look for as we dig into it. My bro and I are both experienced mechanics, but we don't have a lot of experience with this particular engine outside of replacing the timing belt(more on that below).

We have owned the car for 7 years and put about 73K miles on. The timing belt was replaced at about 75k . The engine has always ran fine, but suffers from some of the typical problems I've learned these cars have, such as worn valve guides, low oil pressure at idle and the hot starting thing.

For a long time the engine has whined around the timing belt area when the engine is cold, then goes away after a certain rpm. I attributed it to a timing belt problem but since it isn't driven a whole lot anymore we didn't worry about it.

Here's what happened:

Coming home the other night, the whining noise suddenly reappeared, louder than ever, and at the same time the engine drastically lost power. There was a muffled bang or boom, and the engine all but quit(it's an automatic). It still barely ran on one or two cylinders with the pedal on the floor, along with a rattling noise.

We left it where it was since it was dark, and came back the next day. It turned over and caught, but just barely ran for about 10 seconds and wouldn't restart. The oil is full and clean, and the coolant is also, no mixing. Nothing came out of the engine such as rods or pistons, .

We pulled the cover off the timing belt and found the first clue: The inside(valve cover) edge of the timing belt is severely frayed, and there has been a very significant oil leak occur within a short period of time in the timing belt area since the belt is covered with oil and there is oil leaking down on the frame under and behind the oil filter area. The belt didn't seem overly loose at all, so I'm wondering if there is a worse problem than just a bad belt or tensioner. The oil does not appear to be coming out of the head, it looks like it is lower down. The rattle I describe doesn't remind me of a rod, more like a very loose timing chain.

When turning the engine over, it does sounds uneven as if the timing belt slipped, so....

Any help is much appreciated....

 

[TylerW]

Okaaayyy...

Due to it being extremely cold we haven't done much, but we have determined that it is still in time but appears to have several bent valves. It turns over hard by hand and the cranking speed doesn't increase with all the plugs removed.

Obviously something froze momentarily causing the valves/pistons to interfere, because again, the timing belt is not loose and it did not slip..we checked and rechecked that. The balance shaft belt has never been replaced to our knowledge.

Looking at the labor guide, R&R'ing the head is 10.0 hours..removing the entire engine is only 10.1 hours. By the looks of it, pulling the engine is the next step since there is so much involved in accessing the front cover to even get in the to see what broke or twisted off, etc, and even if we did do that, whatever went wrong is probably serious.

That said, what are the options as far as a replacement(used) engine..? Do we have to stick with an older(90-94) 2.0L or is it possible to upgrade to the newer (95+) engine?


My gut feeling says the balance shaft belt broke and got into the timing belt, or the oil pump locked up and twisted the cog off. I'm curious where all the oil came from tho.

Any comments/advice welcome.

 

[Locke]

Fortunately for you, this engine is just like any other 4 stroke, dohc engines.. nothing really unique here.

You seeing massive oil not coming from the top half would make me think front main oil seal. With oil not falling over your from main bearing correctly, you may have spun your first main bearing. Spinning a main bearing will cause horrible spuealing followed by an almost immediate stall.. Often the motor wont run ever.. Sometimes it will, very hard.

An easy way to preliminarily check for bent valve without removing the head would be to remove the cams and rockers. turn motor to just before TDC on cylinder of choice and stuff the cylinder and compress the spring. Remove the keepers, retainer, spring, and stem seal. wrap some cloth around the jaws of vice grips, and gently lock them onto the valve. (enough to hold it, not enough to damage it). slowly remove your stuffing from the cylinder and move the valve down into it untill the valve is as far down as it will go without dropping it. Now just slide it up and down in the guide. It shouldnt be too hard at all. If it is, may be a bent valve.

An easy way to preliminarily check for internal engine damage (like a broke conrod or snapped ring) would be to remove and inspect the plugs. Physical damage (crushed and mutilated) usually shows a broken conrod. (piston collided with plug) If not damaged, check for metal deposits. Metal deposits on the plug show grinding in the cylinder. A snapped ring and/or piston binding will cause spuealing and shaving large amounts of material from your cylinder walls, much of which may stick to your hot plugs.

By removing the oil pan, you can visually inspect most of the bottom end with the engine in place. A broken rod would be obvious.

Replacement motors are very cheap. You can get JDM 4g63 n/a motors under 35k miles for 600 dollars through JDM Engine Dynamics. Look for them on eBay.

Hope it works out for you.

 

[1.8laser90]

another way to check for a bent valve is to do a compression check if the engine is able to crank over any.. i just bent valves on my 2.0 and when the timming jumped it ran really bad and sound like something broke or was vibrating really badly in the head which turned out to be the valves hitting the pistons.. example of bad compression readings when valves are bent 0,65,100 and 85. those were my readings my engine had with bent valves and it still ran surprisingly when we fixed the timming for a short period and then just ended up getting the cylinder head rebiult for $280 and $100 for a top end gasket set and this was on my 2.0 turbo, the 2.0 n/t should be alot easier to work on if you do the work yourself ..

 

[na90dsm]

blown balance shaft bet causing the timing to skip and bend valves. my motor was otu of time and oen spark plug wire was very messed up and not giving one cylinder spark. the motor ran fine at idle with no aparent timign problems. then i ut load on the motor and it would run like ass.


if you go and take off the drivers wheel. take a peak behind the bottom timing sprocket. there is a slightly larger gear where the balance shaft belt lies. if you see fragments of grinded up belt you blew the balance shaft belt. unless another belt has frayed apart and there are fragments thats what happened.

more of the motors i have parted out bent valves from that little belt then the timign belt itself actually letting loose.

check it out and see. i cant think of anyting else it would be. with all you described to me honestly thats what it sounds like