Car won't start after new main bearings
10-25-2010, 10:07 PM
#1
On The Tree
Thread Starter
Join Date: Jan 2008
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
Car won't start after new main bearings I spun a main bearing, so I took the pan off and pulled the crank out, had the crank polished, since there was minimal wear to the crank, put the new bearings in re-assembled the engine. The engine turns over, but won't start. There is an occasional backfire when turning the engine over. I went and double checked all the electrical connections and everthing appeared ok. I pulled a plug and there was gas on it, so there is gas being injected. I checked the plugs and there is spark. When I installed the crank there wasn't a dot like is shown at ls1howto.com. There was just a small arrow, can I assume this arrow should be treated just like the dot that should be there and I should have had the arrow on the crank in the top position of the rotation, and the dot on the cam gear in the buttom of the rotation. As far as I can tell that is the only thing that I wasn't 100% sure on. Any help is greatly appreciated. I have read several posts on why other peoples cars won't start, and I tried switching the ignition relay out under the hood and that didn't make any difference.
Thanks in advance
Justin
Thanks in advance
Justin
10-26-2010, 12:03 AM
#2
You probably need a new crank position sensor. If it got touched at all with the reluctor wheel when the crank was removed or installed it wont start. I've seen this a handful of times..
10-26-2010, 10:10 AM
#4
On The Tree
Thread Starter
Join Date: Jan 2008
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
nothing was removed from the crank, Just pulled it out and gave it to the machine shop. Would the crank need to be removed again to replace the crank position sensor.
Thanks
Justin
Thanks
Justin
10-26-2010, 12:08 PM
#6
Is it possibe the crank and cam is out of sequence, meaning that when u took the crank out you didn't put it back in lined up with the cam. Dot to dot on the 2 sprokects. sounds like it was not put in exactly where it was took out at
Trending Topics
10-26-2010, 10:03 PM
#10
As long as the crank timing gear is at 12 o clock , the cam gear can be at 6 o clock or at 12 o clock, As long as the crank is at top dead center dot at 12 o clock), the camshaft determines if it on the exhaust or intake stroke, The crank sensor and reluctor ring will keep it firing on the right stroke, On the old style sbc motors you had to time the crank and the distributor because the pickup and the reluctor was in the distributor. So you could get it out of time, but on the new LS style engines ,the pickup is on the block and the reluctor is on the crank shaft witch is timed with the crank instead of the (distributor pickup). So what im trying to say, is if you put the cam and timing chain gear in at 180*out ( cam gear dot at 12 o clock) , you will just need to turn the crank 360* and it will put the cam gear at 6 o clock with out pulling the cam gear.. The crank turns two to one with the cam. The only time i want the timing on the intake or compression stroke is when i adjusting the valves. Before any one nails me to the cross on this, think about what im saying. Check and see if the reluctor ring is damage or the crank sensor or the cam sensor is bad, and also check and see if the cam sensor wire didnt get pinched between the block and bellhousing and shorting the cam sensor out.
Last edited by Randy WS6; 10-26-2010 at 10:09 PM.
10-26-2010, 10:08 PM
#12
As long as the crank timing gear is at 12 o clock , the cam gear can be at 6 o clock or at 12 o clock, As long as the crank is at top dead center dot at 12 o clock), the camshaft determines if it on the exhaust or intake stroke, The crank sensor and reluctor ring will keep it firing on the right stroke, On the old style sbc motors you had to time the crank and the distributor because the pickup and the reluctor was in the distributor. So you could get it out of time, but on the new LS style engines ,the pickup is on the block and the reluctor is on the crank shaft witch is timed with the crank instead of the (distributor pickup). So what im trying to say, is if you put the cam and timing chain gear in at 180*out ( cam gear dot at 12 o clock) , you will just need to turn the crank 360* and it will put the cam gear at 6 o clock with out pulling the cam gear.. The crank turns two to one with the cam. The only time i want the timing on the intake or compression stroke is when i adjusting the valves. Before any one nails me to the cross on this, think about what im saying. Check and see if the reluctor ring is damage or the crank sensor or the cam sensor is bad, and also check and see if the cam sensor wire didnt get pinched between the block and bellhousing and shorting the cam sensor out.
10-27-2010, 07:06 AM
#15
10-27-2010, 07:11 AM
#16
I'm going to add to this....if the cam sensor is not updating the pcm it is going try using the info it already stored in the pcm and its not going to start if the cam was timed 180 degrees out from where it was when you pulled it apart. It is going to fire 180 out.
10-27-2010, 08:39 AM
#17
That's the craziest thing Ive ever herd I guess somebody had to brake out the hammer and nails LOL 
. I am trying to help this guy,By not having him tear down the front of engine to turn the cam gear. The cam gear also has its own rulutor ring machined into it , so you cant get it out of time by 180* but you can get it out of mechanical time any were between 1*to 179* or 181* to 359* or lets say miss alignment by a tooth or more on the timing gears but not at 180* and the PCM has nothing to do with what we are talking about to a point , its electronic and reads what the crank & cam sensor tells it to read. I build my own engine and do my own programing so i know a little about it, but i guess not as much as you.So i guess ill just back away and let you handle it. Sorry spdrcr7882 for not trying to help you figure out your problem or try to help you see how it works.
. I am trying to help this guy,By not having him tear down the front of engine to turn the cam gear. The cam gear also has its own rulutor ring machined into it , so you cant get it out of time by 180* but you can get it out of mechanical time any were between 1*to 179* or 181* to 359* or lets say miss alignment by a tooth or more on the timing gears but not at 180* and the PCM has nothing to do with what we are talking about to a point , its electronic and reads what the crank & cam sensor tells it to read. I build my own engine and do my own programing so i know a little about it, but i guess not as much as you.So i guess ill just back away and let you handle it. Sorry spdrcr7882 for not trying to help you figure out your problem or try to help you see how it works. Last edited by Randy WS6; 10-27-2010 at 02:17 PM.
10-27-2010, 11:41 AM
#18
On The Tree
Thread Starter
Join Date: Jan 2008
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
When we were turning the engine over, it was backfiring some and my brother ( who is pretty knowledgable about engines) said it seemed like the engine was turning too easily, almost like it wasn't building compression, this could just be our observation, but if the cam was 180 out, would this keep the engine from building compression? Just guessing here. Ill Check the cam sensor wire to see if it's pinched
Thanks for the help
Justin
Thanks for the help
Justin
10-27-2010, 12:44 PM
#19
When we were turning the engine over, it was backfiring some and my brother ( who is pretty knowledgable about engines) said it seemed like the engine was turning too easily, almost like it wasn't building compression, this could just be our observation, but if the cam was 180 out, would this keep the engine from building compression? Just guessing here. Ill Check the cam sensor wire to see if it's pinched
Thanks for the help
Justin
Thanks for the help
Justin
Im not trying to be a smart *** or calling any body dumb *** , im just telling how the crank & cam and sensors works together on a four stroke LS1 style engine.
