CIS Injector Sleeve w/Backfire Damage??

[VFR750]

Pulled CIS a couple of weeks ago. 121,000 miles, no issues. Looked at the system today, and I was surprised to see this damage. Car had issues with occasional backfire. Pop-off valve always saved the day. I had sealed the injector sleeves with RTV to prevent vacuum leaks.

Ever see this before? #2 cylinder sleeve is melted. All others look fantastic.


Close up


I think it must be due to backfires. #2 must have been the frequent source of the backfires. Looked down at the valve after the CIS was removed and saw no visible damage to the valve. So it's a little mystery.

I bet air was leaking past the o-ring on the injector, but was the backfire blowing past the o-ring?

[john walker's workshop]

do a leakdown test on that cylinder.

[NeedSpace]

My injector literately fell out of the sleeve while I was removing my CIS system from my 1976 2.7. The other 5 are quite snug. I purchased some new o-rings and a new sleeve. This is what the replaced sleeve looks like....



FYI, the chewed bit at the bottom was due to me taking it out, however, the rest that looks like a turd was how it came out.

After reading around, it looks like this was the unfortunate destruction of an intake backfire. I assume it was a vacuum leak that caused the intake backfire. I am planning on checking the other 5 cylinders and seeing they look like (for possible replacement). Is there anything else you would recommend checking while the engine is out?

[timmy2]

Needspace, Plan to change all of them, they get brittle and you'll probably crack one or 2 when pulling them out.

[NeedSpace]

Timmy,

You are right. This morning, I checked the other ones, they all look like this...another purchase...Funny, when ordering I thought I should order sleeves all the way around...

[theiceman]

remember there are two sets of o rings here. The o rings that seal the sleeve to the runner and the other that seal the injector to the sleeve. make sure you get them all.

[NeedSpace]

Iceman,

thanks, I'll make sure to do that. Thanks for supplying the photos.