Drive on a bent valve?

[RipperXX]

Theres a decent possibility I have a bent valve, im thinking on the #1 cyl since the plugs out it are a little funky.


Would you drive on it if it was that or a MKIII Supra you dont quite trust yet with a huge boost leak that drinks gas worse than any V8 I have ever seen.?



BTW just changed T-belt and I think there could be some vacume/boost leaks so im not ruleing anything out just yet...

 

[dsmrunaway1]

Funny u say that... i bent valves..(9 of them ) well anyways what happend to me when i had the valve problem was that when i came to a stop from like going 20mph to slow down to catch a stop sign it would stall out....i had tons of smoke out my exhaust...serious blowby....but yea the stalling and rough rough idle was...really really bad... prob not as serious as ur would be due to the fact i have prob like 8 more bent valves then u...which means that my compression is even worse.....but now 1mm os valves nitrated coated should do jus swell...

 

[RipperXX]

Actualy im starting to think it's not a bent valve, tomarrow I should be able to do a compression check.

The ignition timeing is advanceing to 15* at idel and theres like 9-10 vac, I retarded the timeing back to factory specs 5* and it didn't help a bit, just made the car even slower, so I put it back where it was.. or close enough.

 

[psychlow]

If it's consuming that much gas, it's likely you're going to end up with washed out piston rings.

 

[RipperXX]

It's not doing that bad on gas. And I just did a compression test it came back a little out of spec but defently no bent valve


#4 140
#3 142
#2 125
#1 135

 

[psychlow]

You're fine to drive on that, then. If it were a bent valve, you'd get no compression, therefore no combustion on that cyl. You'd just be sending gas down into the combustion chamber, and that's what I was worried about.

Since that's not the case, I'd start looking at other things like your A/F and how your timing looks. Like you said, it's a little out of spec, but your vac readings shouldn't be that low unless you have uber-race cams, or you're at 12,000ft elevation.

 

[RipperXX]

Well heres everything I know thats wrong or odd.


Base ignition timeing when checked was off the scale, retarded to spec and it was sick as a two leged dog thats been shot, put it back to 15* (was around 18). Timeing is ON, we have checked it like 3 times now. Vacume has been low for a while and got worse over time. We had to rase the idel speed as well, which to me makes no since if it was that large of a vacume leak shouldn't I have to lower the idel?


The only two things I can think of are that the ghetto warped tin block off plate I made for the EGR valve has burned though and it's just continuesusly puting exhaust in the intake manifold. Or I have the fireing order wrong???



Pretty sure I dont though, same as it has always been since I got the car, I had it backward on my old car once but hell it wasn't this bad. So since the hayness manule explains it in some ####ed up round about way I just drew it out when i got the car and first did a tune up.

 

[half-cocked]

Just curious have you done a leak down?

 

[RipperXX]

You mean when you poor oil in a cyl and see how long it takes to drain into the block? If so then no, nore do I plan on it. It use's like 1 & a half quarts of Mobile 1 wana be syn every oil change, I dont think thats to bad for a 105,000 mile engine.

 

[psychlow]

A leakdown test is when you pressurize the combustion chamber with air and see how long it takes to leak down. You can also listen for leaks and see where the air is escaping to determine what needs to be checked/reworked.

If you have a large enough vacuum leak, it can run lean enough at idle to cause a decrease in idle speed.

 

[RipperXX]

If I could find my damn boost tester I would, looks like im going to have to make two of them this thursday..


One for tha Talon and one for the Supra...

 

[psychlow]

If I could find my damn boost tester I would, looks like im going to have to make two of them this thursday..

Just an FYI - A leakdown tester is a little different than a boost leak tester. A leakdown tester screws into the sparkplug thread and has a check valve that will only allow compressed air to enter the cylinder, with a gauge to measure the pressure as the cylinder leaks down.

 

[RipperXX]

In that case no I have not, and why would I do so?

 

[psychlow]

Not sure - someone else, above, asked if you had done one.