l18 compression test

[racerx]

Did you loosen the adjustment nut (14mm) towards the back of the back of the car?  if you did this and adjustment was not possible then strong possibility that you can't adjust anymore - valve has sunk.  Here are some possible cures 1).  take out the adjustment nut and grind it down some, try this first.  2).  if #1 does not work then get a head job, no pun intended, 3) or you can find a refurbished head and install 4). another thing to consider is to rebuild total engine, this will depend on how many miles and condition of engine block and/or if you are seriously thinking about keeping the car or 4). buy a total rebuilt engine and use your old one as a spare for later use.  A lot will depend on your finance, skill set, tools, time, a place to work on your car (garage) and not under a tree

[datzenmike]

You can remove the rocker and mouse trap spring to get at and remove the pivot post and the lock down nut. This nut can be ground down thinner and give you more adjustability to get your valve lash back. This is not a cure for a receding valve but, it can keep you on the road while you source a new head.

[sanyantho]

You can remove the rocker and mouse trap spring to get at and remove the pivot post and the lock down nut. This nut can be ground down thinner and give you more adjustability to get your valve lash back. This is not a cure for a receding valve but, it can keep you on the road while you source a new head.

This is what I did as advise by you when I first brought the truck. Now the mouse trap spring is very weak and not able to hold the rocker to the povit post very well causing a miss and backfire when I press the gas pedal.

[banzai510(hainz)]

if you have the correct feeler gauge the rat trap spring isn't that hard. How about swap to another itf it moves then you have a proplem I hightly dought it.  it should not back fire if the if the valve lash is good sinking valve or not. the valve sinks over time. Unless the valve seat is wiggling in the head. then not closing but that will give a missing cylinder type of proplem.

 

rat trap is more of a guide to help keep the rocker alighned if anything(Ok I just made that up but that's what I think its for)

[racerx]

Also if your valve is sinking, your compression for that cylinder will be low.  My intake valve #7 sunk and that piston had low compression like 90 or so.

[datzenmike]

This is what I did as advise by you when I first brought the truck. Now the mouse trap spring is very weak and not able to hold the rocker to the povit post very well causing a miss and backfire when I press the gas pedal.

 

The mousetrap spring has nothing to do with back firing. It has nothing to do with closing the valve. That's the job of the valve spring.

 

Assemble and check the valve lash.

 

If still back firing, the valve may already be burned from being non adjusted for too long. Possibly the seat is now loose.

 

 

http://community.ratsun.net/topic/69078-more-l-valve-adjustment-for-sunken-valve/

[sanyantho]

The mousetrap spring has nothing to do with back firing. It has nothing to do with closing the valve. That's the job of the valve spring.

 

Assemble and check the valve lash.

 

If still back firing, the valve may already be burned from being non adjusted for too long. Possibly the seat is now loose.

 

 

http://community.ratsun.net/topic/69078-more-l-valve-adjustment-for-sunken-valve/

I assemabled and adjusted the valve lash. It ran great for a month, but started backfiring again. I also just notice the my belt is bad and in need of replacement.

[banzai510(hainz)]

if belt is loose then your getting a weak signal. Its a possibility. Happen to me on my 510 with loose alternator belt. but really its rare.

 

 

Sinking valve means FIND another head soon as youl run out of gap then it wont adjust any more and loose that cylinder.

[sanyantho]

if you have the correct feeler gauge the rat trap spring isn't that hard. How about swap to another itf it moves then you have a proplem I hightly dought it. it should not back fire if the if the valve lash is good sinking valve or not. the valve sinks over time. Unless the valve seat is wiggling in the head. then not closing but that will give a missing cylinder type of proplem.

 

rat trap is more of a guide to help keep the rocker alighned if anything(Ok I just made that up but that's what I think its for)

Hainz, the valve is adjustable and is adjusted correctly. But the rocker can be moved around by my finger. The rest of the rockers with strong mouse trap spring wont move at all.

[sanyantho]

Did you loosen the adjustment nut (14mm) towards the back of the back of the car? if you did this and adjustment was not possible then strong possibility that you can't adjust anymore - valve has sunk. Here are some possible cures 1). take out the adjustment nut and grind it down some, try this first. 2). if #1 does not work then get a head job, no pun intended, 3) or you can find a refurbished head and install 4). another thing to consider is to rebuild total engine, this will depend on how many miles and condition of engine block and/or if you are seriously thinking about keeping the car or 4). buy a total rebuilt engine and use your old one as a spare for later use. A lot will depend on your finance, skill set, tools, time, a place to work on your car (garage) and not under a tree

Im going with #3.

[banzai510(hainz)]

well if the lobe is not pushing on the rocker where its pointing up, the rocker will wiggle. This is how I ck my valve lash off the bat if my valve cover is ever open. if fells tight then I adjust. if wiggles I know the valve is closed.  if tight then could have a compression cylinder loss issue.

 

well if you buy a spare head swap a rat trap spring. But Just me I don't think it will be your  issue

[racerx]

If you do buy a rebuilt head, make sure they installed hardened valve seats not brass. Also ask them if it has been shaved or not and what they did to the valves, , springs, new or not and cam.  If you are going to install the cylinder head watch Hainz video over and over again and over again, til you get a very good idea, much clearer and practical  than reading those books by Clymer or chiltons. You can read them but more for steps and reference.  You will find that torqueing the head specs will vary from one book to another. And buy quality gaskets and timing chain kits from NISSAN or TSUBAKI.  Other Ratsun members may know more quality parts..Good luck  and keep us informed.

[Doctor510]

Make sure that the lash pad is not installed up side down (ears up), sounds hokey but it happens

[sanyantho]

Should I change the water pump since I am right there? If yes, where should I buy?

[Draker]

I probably wouldn't.. unless you suspect there is an issue. It's not like other cars where it's a major pain in the ass to repair. it's just a few bolts and your done. They don't cost a lot though.. so if you want to you can. rockauto.com

[datzenmike]

Never fix what ain't broken.

 

Set the lash on another valve and I bet the rocker wiggles too.

[racerx]

If u do change waterpump, change ur thermostat. Check hoses and belts, too. One affects the other. Just dont get ur stat at autozone.

[sanyantho]

Never fix what ain't broken.

 

Set the lash on another valve and I bet the rocker wiggles too.

All valve lashes has been set. The only one moving up and down a little is the one with the weak mouse trap.

[datzenmike]

All valves if set should move up and down very slightly, this is what the clearance is for.

 

Swap a spring from another valve, it'll be the same. Regardless, this isn't your real problem, it's the valve is sinking. Actually sinking upward on the valve spring end of the rocker which forces the adjustment end to need to be lower to get the adjustment.

[banzai510(hainz)]

why change the water pump? if not leaking why bother.

 

i

 

You have to pull the radiator?

 

 

find a Atsugi pump if at all possible. next GMB brand(japan)  the rest are china now it seems

[datzenmike]

If you find a good quality cast impeller water pump on sale, sure, get it and save for a rainy day. Never hurts to have spares, but change a good running pump?

[racerx]

What about Beck Arnley or Gates, are they good WP?

[sanyantho]

I wont change the water pump since its in good condition. I will have to replace the gasket tho. Thanks for the all good advice guys! :thumbup:

[banzai510(hainz)]

well its uip to you on that. If you have to replace the gasket.

The GMB pumps come w a gasket if I remeber right.

 

if it leaks water make sure it not from the weep hole in the pump. then the pump is going bad.

[Doctor510]

Weak mouse trap springs can be fixed.  Just squeeze the "bar" and the "legs" closer together.