Jump to content

Color of my exhast valves


ejin4499
 Share

Recommended Posts

While I had my exhaust manifold off I noticed that 5 of my exhaust valves were bone white and one of them was black. I've been trying to find a definative description of what the colors mean and what if anything should be done about it. Anyone have any info that might explain why one would be black while the others are white?

Thanks

Link to comment
Share on other sites

Its been my experience that valves are usually dark in color unless they have some hight heat coating on them (TBC/ceramic race engine stuff).

Ideally(not coated) they should be smooth and have a dark gloss or semi gloss shine.

My guess is you may be running lean, too hot or both. How do your spark plugs look? White? Ashy?

Maybe cloged injectors not spraying as much they should.

 

Its a start,

Maybe somone that knows more will chime in...

Link to comment
Share on other sites

Its been my experience that valves are usually dark in color unless they have some hight heat coating on them (TBC/ceramic race engine stuff).

Ideally(not coated) they should be smooth and have a dark gloss or semi gloss shine.

My guess is you may be running lean, too hot or both. How do your spark plugs look? White? Ashy?

Maybe cloged injectors not spraying as much they should.

 

Its a start,

Maybe somone that knows more will chime in...

I'll take a look at my spark plugs this weekend and let you know.

If the water pump wasn't moving as much water as it should, would that lead to a engine that is running to hot even though the temp gague show only about half way?

 

Also would that have anything to do with my idle not being stable? When its cold its steady at 750 but when it warms up sometimes it will waver between 1000 and 250 and even sometimes stall.

Edited by ejin4499
Link to comment
Share on other sites

I'd read the cylinders by the condition of the spark plugs, not by the valves. If your idle runs in between 1k RPM and stall, yeah, there is a problem...

 

Check the ECU for stored codes (Garage/How To section), clean your MAF and check the connection/wiring, download the 1994 FSM (pinned in the Garage section) and maybe check the TPS? Check for vacuum hose leaks...

 

B

Link to comment
Share on other sites

I'd read the cylinders by the condition of the spark plugs, not by the valves. If your idle runs in between 1k RPM and stall, yeah, there is a problem...

 

Check the ECU for stored codes (Garage/How To section), clean your MAF and check the connection/wiring, download the 1994 FSM (pinned in the Garage section) and maybe check the TPS? Check for vacuum hose leaks...

 

B

I'm dying the death of a thousand pinpricks. tried spraying carb cleaner around the heads and around hoses the engine didn't start to race but what I did notice is just about every one of my vacuum hoses has more cracks than a room full of proctologists. I'm going to start with replacing all of those and checking my spark plugs. The plugs are only about 1000 miles old would they still show a problem?

Link to comment
Share on other sites

*snort*

Nice analogy!! :D

 

Yeah, start with the vacuum lines, it's pretty cheap and easy and sounds like it will be trouble soon anyway. Go ahead and check all vacuum diaphrams for proper function while you are at it.

 

Valve coloration may not be a recent thing, may have to do with hot spots in the head/manifold, etc. Spark plugs, on the other hand, show the immediate condition the best. Yes, 1000 miles is more than enough, 100 would probably suffice. Pull them and if you aren't sure, take some good pictures of them and post. We'll figure what is going on...

 

B

Link to comment
Share on other sites

*snort*

Nice analogy!! :D

 

Yeah, start with the vacuum lines, it's pretty cheap and easy and sounds like it will be trouble soon anyway. Go ahead and check all vacuum diaphrams for proper function while you are at it.

 

Valve coloration may not be a recent thing, may have to do with hot spots in the head/manifold, etc. Spark plugs, on the other hand, show the immediate condition the best. Yes, 1000 miles is more than enough, 100 would probably suffice. Pull them and if you aren't sure, take some good pictures of them and post. We'll figure what is going on...

 

B

I thought it apt :)

 

ok so I pulled the spark plugs and they all looked good. I will post pics of worst one, meaning the one with the most deposits.

I have been looking through the manuals it looks like the 94 is the closest to mine. Pathfinders 90-95 are just about the same under the hood right?

 

while under the hood a little later I noticed a hissing noise but could not find a source. It seems to be coming from the back of the engine. I am only aware of one small vacuum line back there and I just replaced it about a week ago. Is it possible that I have a blown gasket back there ??? What should I be looking for???

Edited by ejin4499
Link to comment
Share on other sites

Yes, 94 was the first distributed electronic copy so that is what you will have to go with. It is fine for under the hood and the majority of other things. The main differences are the dash and related systems, bumper/fog lights, tie rod end tapers, etc.

 

With the spark plugs, one important thing is that they are all similar in coloration/deposits so things are the same in all cylinders. Yeah, post it up...

 

I can't help with the hiss; I can't hear it from here...

 

B

Link to comment
Share on other sites

Yes, 94 was the first distributed electronic copy so that is what you will have to go with. It is fine for under the hood and the majority of other things. The main differences are the dash and related systems, bumper/fog lights, tie rod end tapers, etc.

 

With the spark plugs, one important thing is that they are all similar in coloration/deposits so things are the same in all cylinders. Yeah, post it up...

 

I can't help with the hiss; I can't hear it from here...

 

B

ok got part of one problem and found two new ones.

 

Ok so the part of the problem that I found is that the vacuum line on the fuel pressure regulator on the back of the motor didn't fit as well as I thought it did. A little rtv on the end of the line while it was on the nipple saw that straight I think... maybe.. still hearing a strong sucking noise.. I wasted a whole can of carb cleaner trying to track that down. But on the plus side my truck no longer stalls or idlehunts when I step on the cluch during deceleration. I still have a small hesitation when I stomp on the gas which I think is related to the suspected vacuum leak.

 

Any ways the problem that I just discovered is that one of the exhaust manifold studds that I just replaced only had thread on the bottom half of the hole that the stud goes in. I gues helicoil is the only way to go on that ???? Would be greatful for any input on the issue.

 

second problem I discovered is that the brass fittings on my oil filter relocation kit are leaking badly. I wrapped som wire between the brass fitting and the plastic spacer and that helped massivly. Now it only leaks a small amount when driving instead of spraying when idling. Do these universally suck and I wasted money or did I happen to just get a bum one??

Thanks

Link to comment
Share on other sites

Good, but, get the right line or put a hose clamp on it if it is close enough, don't count on RTV for something like this; it will let you down IMO. Then chase the rest... ;)

 

A cold form tap may help if there is enough thread, but no gaurentee. Yes to drill out and put in a threaded insert. Don't go deeper than it is, you may be close to a water channel. I've had good luck with Heli-coil but have not used it with this application. All in all, what ever you use, make sure to do it right the first time. I'm a machinist, so if you have any questions, ask...

 

Are they the swivel fittings?? Mine leaked also so I replaced them with solid units...

Regardless, if it leaks, you have to replace it with something better. :shrug:

 

B

Link to comment
Share on other sites

Good, but, get the right line or put a hose clamp on it if it is close enough, don't count on RTV for something like this; it will let you down IMO. Then chase the rest... ;)

 

A cold form tap may help if there is enough thread, but no gaurentee. Yes to drill out and put in a threaded insert. Don't go deeper than it is, you may be close to a water channel. I've had good luck with Heli-coil but have not used it with this application. All in all, what ever you use, make sure to do it right the first time. I'm a machinist, so if you have any questions, ask...

 

 

Ok I looked up cold form tap and it doesn't sound like that would work as the first half of thread was stripped before I got the truck and the rest stripped out as I was tightening the new stud in place (they had used a bolt which still allowed the gasket to blow out)

 

Should I helicoil the rest of the studs on that side of the head so I keep the same thermal expansion across all of the studs or is no big deal?

 

Basic theory of the helicoil as I understand it is

 

clean out existing thread remnants with recomended drill bit

thinking I'll get a dowel measure depth then mark drillbit so I don't over do it

tap the hole with supplied tap which resembles the pictures of a cold form tap.

gently at the proper angle

:dirty mind filter: having never tapped anything other than a keyboard is it self aligning or is there a trick to get it in there straight:close dirty mind filter: ;)

back out shaving frequently

use lots of lube thinking penetrating oil

insert threaded insert which looks like it just threads in maybe some type of lock tight may be in order ?

insert stud

Profit :)

 

Are they the swivel fittings?? Mine leaked also so I replaced them with solid units...

Regardless, if it leaks, you have to replace it with something better. :shrug:

 

yes they are the crappy swivel fittings. I know I'm looking for somthing 3/4" but beyong that I'm a little lost.

do I get all new lines

what are the specs other than 300 psi and 3/4"

any particular brand or material

do I just get new fittings cut the old ones off and inset these ( where get. don't trust OSH )

Ok thats as lucid as I get after 10 :coffee!:

Thanks for the help

Edited by ejin4499
Link to comment
Share on other sites

Ok, cold form tap only works when there is something left to form so forget that.

 

Just fix the one stripped one, I wouldn't mess with the others unless you want to replace all the studs to the upgraded ones. You have the basic idea for tapping and helicoiling, and yes there are tricks to tapping straight. Use a tapping block (flat piece of metal with a hole in it just larger than the tap that you lay one the surface and tap through) or a tap guide wwhich alsp teeps the tap in alignment. Read this...

http://www.nissanpathfinders.net/forum/index.php?showtopic=16196

 

 

For the leaking swivel fittings, I had the same problem and simply replaced them with solid barb fittings. Just cut the old hose off right at the old fitting, and slip the new barb fitting in and tighten the hose clamps. I'll have to check to see what size they were. I want to say 5/8". Read this...

 

http://www.nissanpathfinders.net/forum/index.php?showtopic=20577&st=0&p=412746&hl="oil%20filter"&fromsearch=1entry412746

 

:beer:

 

B

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...