CA18det low or no compression need help!!

hondsemoer · Post by **hondsemoer** » Sun Dec 09, 2007 8:00 am

Hi there I'm new to this forum its been a great help sofar but I'm struggling with my 200sx for the past 6 months now. I have been driving the car for the last 3 years and do all the work myself keeping it running. I blew the head gasket about 6 months ago and since then its been blood sweat and alot of pain.
I took the head of and took it to the engineers to get it completly overalled,but when i put thehead back on and tried to start it the motor had no compression you could actually turn the crank by hand! Any Ideas what I should do next? I have replaced the valve lifters and all gaskets the head was pressure tested and came back fine! I then stripped the sub assy and replaced the rings and bearings and still no compression! So guys please help!

widowmaker · Post by **widowmaker** » Sun Dec 09, 2007 8:10 am

hello, mmm sounds like you need to take apart and have a good look - you missed something big and basic there (hopefully) (were you in a hurry by any chance?)

helpful, innit?

hondsemoer · Post by **hondsemoer** » Sun Dec 09, 2007 8:18 am

I've taken it apart many times! I am in hurry to get it running asap! There is compression when you take the cams off and put the plugs in but as soon as you put the cams and lifters back theres no compression I put the old lifters back but still the same thing! Can it be the valves thats is seated to deep with the regrinding of the valves?

n1smo200sx · Post by **n1smo200sx** » Sun Dec 09, 2007 1:50 pm

When they reseated the valves it moved up into the head,now the cams is pushing the valves open all the time..You need to reshim the head to get the clearances right.

Draco · Post by **Draco** » Mon Dec 10, 2007 9:07 am

Something I don't think you would miss because it seems you know engines but sometimes some guys turn the exhaust an intake cams around.....are you sure it is the right way around....?

hondsemoer · Post by **hondsemoer** » Mon Dec 10, 2007 9:38 am

The cams are the right way round I think the valve clearance must be wrong. The valve lifters must I press them down before I put them in? Can the valve lifters be to tight or the valve springs to weak because the head overheated?

Vlade · Post by **Vlade** » Mon Dec 10, 2007 10:32 am

hondsemoer wrote:The cams are the right way round I think the valve clearance must be wrong. The valve lifters must I press them down before I put them in? Can the valve lifters be to tight or the valve springs to weak because the head overheated?

It can but its rare, if the lifter has seized it can cause it to happen.

Not really hey, I'll go with what Nismo said... do the following test, bit of a schlep, but only way to tell if you have a valve clearance problem without removing the head

Remove the cams and swing engine and do compression test, with no cam belt on... Important to remove the cams otherwise you'll end up with bend valves, also remove the other cylinders spark plugs while you do this...

If you have compression while you do this, you know you have a valve clearance problem.

hondsemoer · Post by **hondsemoer** » Mon Dec 10, 2007 9:39 pm

Hi guys I took the head off again and put the cams back on the exhaust side there is about 0.1mm clearance checked it with a feeler gauge. However on the intake side there was no clearance just on one valve so I'll take the head back to the engineers to sort out the clearance tomorrow and see what happens! Does anyone what the clearance must be so that I can check it when it comes back? Thanx for the help guys!

antman · Post by **antman** » Thu Dec 13, 2007 7:15 am

Hi hope you are sorted, if not this my experience. Had a similar problem with ather makes of cars, normally when the head has been skimmed and the valves/seats have been recut valves move towards the hyd valve lifters. I assume you used the same lifters and if std they are hydraulic units which if you have not bled them will give you no clearance eg low or no compression. (keeps valve slightly open due to running on the base circle of the cam) Either use new lifters which will pump up with oil, noisy at first but will quieten or bleed your old ones.