Bad fuel injector?

[Mikel]

I was finally able to get an adapter for my compression tester. #1 had 25 psi. 2,3,4 and 5 had 145-155PSI. #6 was almost as high, but somehow it seemed a bit erratic.

I pulled the head and I found the #1 intake valve to be very slightly bent. One can see the carbon deposits on one side of the valve seat. #6 is starting to develop the same. Tomorrow I'll be replacing those two valves. What could have caused this?? I see no marks of foreign objects in those cylinders, or of the valves hitting the pistons. Am I better off replacing all intake valves??

At least now I know what the problem is :yelclap:

Thank you all.

 

[Talyn]

I don't see a reason to replace the rest of the valves since the problems were isolated tot hose two cylinders. The valves won't hit the pistons because it is a non interference engine. I don't know what the cause could be. Are you the first owner?

 

[Mikel]

I don't see a reason to replace the rest of the valves since the problems were isolated tot hose two cylinders. The valves won't hit the pistons because it is a non interference engine. I don't know what the cause could be. Are you the first owner?

No. I just bought it with 170K miles. It had this problem already. The good news is that the crosshatching is still visible in all cylinder bores.

 

[O-Gauge Steamer]

No. I just bought it with 170K miles. It had this problem already. The good news is that the crosshatching is still visible in all cylinder bores.

Which is a good indication of the condition of the rings. Good find on the valve. Be sure to clean the valve seat when installing the new valves. If you have not done it before, get woth someone who has. Not difficult to do, but easy to mess up...

 

[Ecomike]

I have no idea, but I also curious what bent the valve stem.

I would take the head to head shop, since you have it off, and have them clean, inspect and at least install new valve seals, and possibly new valves (?), check the head for flatness, and get their opinion on the valves!

When I pulled the head on our 89, it had boulder sized hard carbon chunks, near the size of golf balls, all over the top of the head from running hot....and prior owner abuse.

 

[volaredon]

SUGGESTION; Since you now have a 2nd set of injectors take one set to a Fuel injection service place (there are several they usually advertise diesel injection but can and do service gas ones) the one I use does them for $15 per injector; flush test and replace teh filier screens; you basically have the same as the "rebuilts" listed above for ~$40 ea. if youre anywhere near me I can tell ya of 2 places; one outside Kankakee IL (Triangle Diesel) and one up I 55, near IL 83 (Willowbrook), I think they are called Midwest fuel Injection; never dealt with them since they are an hour away and Triangle is like 10 minutes. but I know they do the same thing.

theres also occasionally a guy that advertises this service in the auto parts section on Chicago CL. He's a lil more expensive;
IDK what Midwest would charge like I said never had reason to find out with this other place as close by as they are.

 

[Talyn]

I've used www.cruzinperformance.com before with good results. Their site is currently down for me though. Hopefully its just a glitch.

 

[Mikel]

It's all back together and it runs perfect

Thank you all.

 

[Talyn]

All you did was replace the valves?

I still wonder what would have bent them... maybe a stray piece of carbon or other garbage got trapped between the valve and seat. Maybe the previous owned did something stupid.

 

[Mikel]

All you did was replace the valves?

I still wonder what would have bent them... maybe a stray piece of carbon or other garbage got trapped between the valve and seat. Maybe the previous owned did something stupid.

I lapped all the valves and replaced the valve seals. The valves in cyls 1 and 6 had HORRIBLE contact patterns and took a lot of lapping.

 

[Talyn]

It was probably like that for a while and produced the bad contact pattern. Since you had to do much lapping I would check the preload on those two cylinders. The valvetrain is pretty forgiving being hydraulic, but you never know.

 

[Ecomike]

What is preload, and do you check it?

 

[Talyn]

Lifter preload. Its the amount the pushrod and everything above it pushes the lifter down. Any change in the valve train can change preload. There are a few ways to do it. Its always checked with the cylinder at TDC and the lifters on the base circle of the cam. You will want to loosen the rocker bolts and left the lifters come up. Then tighten the bolts to take out slack in the push rod, gently spinning it with your fingers while tightening the bolt by hand until the pushrod stops moving is one way. That is the o lash point. Now you have to measure. Some people mark the push rod with a straight edge off the head surface. I like to put a dial indicator some place on the rocker arm. Others count the turns the bolt goes until torqued. ... so now mark or o your dial indicator or get ready to count turns. Now you want to torque the rocker bolt down. Then give the lifter some time to bleed down. If you did the mark method, put a second mark on the push rod using a straight edge. If you used a dial indicator just read it. The dial indicator will show your preload. With the mark method you pull the push rod out and measure the space between the two marks which is your preload.

Stock preload is 0.020 and 0.060"

I probably did a crappy job of explaining it so read here: http://www.cranecams.com/pdf-tech-tips/hydro-lift.pdf