Sounds like an exhaust leak but what is it?

[Fj moneypit]

So I got the 2F dialed in and drove on the freeway and back and was running great. On the last leg of drive it started sounding loud and had a loss of power. I thought maybe my headers which had a small hole. Replaced with new headers. Still had same problem. Check for head gasket leak and did a block test and all was good. Checked compression and all but #5 were ~ 160. #5 was 140. Readjusted valves checked for vacuum leaks with carb spray around intake. I’m at a loss of what else to check. Any help appreciated.

 

[whitey45]

Have you confirmed it’s hitting on all 6 cylinders? How do the plugs look? Sounds like a misfire issue?

 

[ibinazbass]

Check timing? Spark plugs? Choke working properly? How much vacuum is it pulling at idle? Exhaust restriction?

 

[Fj moneypit]

Thanks. Spark plugs and wire and coil all new. Did timing but may check again. I had timing get off before. Idles good. Good when in neutral but on the drive is when I noticed it.

 

[ibinazbass]

Do you have a vacuum gauge?

 

[Fj moneypit]

Do you have a vacuum gauge?

yes. I did check vacuum and did a lean drop in the past but will check again

 

[middlecalf]

What is sounding loud? What’s the story on the rest of your exhaust system?

 

[Solace in Solitude]

Vacuum loss? You didn’t say what year.., don’t forget the vacuum advance module, on the dissy, if you have one. I had a serious vacuum leak at that vac adv diaphragm. With an o board vacuum gauge, you can see what’s happening while you drive.

Clutch slipping?

With an onboard tach, you could see if the “loud” is engine revolutions.

More info would help... what conditions cause the change? Like uphill, foot to the floor, etc.

 

[Fj moneypit]

What is sounding loud? What’s the story on the rest of your exhaust system?

Hard to pinpoint. Sounds like an exhaust leak but the headers are new and the muffler is not to old. Feels like a bit of powe loss.

Vacuum loss? You didn’t say what year.., don’t forget the vacuum advance module, on the dissy, if you have one. I had a serious vacuum leak at that vac adv diaphragm. With an o board vacuum gauge, you can see what’s happening while you drive.

Clutch slipping?

With an onboard tach, you could see if the “loud” is engine revolutions.

More info would help... what conditions cause the change? Like uphill, foot to the floor, etc.

All good questions/thoughts. The fj40 is a 71’ with a 75’ 2F. No smog stuff. Just checked vacuum and getting around 17. Good vacuum to dizzy when pull and replace hose. When in neutral and revving engine you don’t here it. I here it when I drive. It’s sounds like exhaust leak. That kinda pitter patter noise. Maybe clutch?

 

[Fj moneypit]

 

[JohnnyC]

I had a similar issue... happened mostly when it got warm/hot

Turned out to be my header to y-pipe was barely holding on ... slid out from its slip jointed and band clamped areas ... both sides on the y-pipe

When it got hot it would expand the header and push past the pipe

Exhaust leak

It was so slight but it was there... slid it back in and clamped it down hard... it was good for a day then it did it again

My muffler /back was pulling on the connection ... and when it got hot it would start to slide and separate again

Removed my entire system and made sure there was no tension pulling back... never happened again

Do not know if that is anything that you have going on... but... it’s a thought... things get hot and expand/move

Sure the header is seated correctly on the head? Maybe a crack on the header that separates when it warms up?

Just throwing that out there

Good luck... keep it up... you’ll get to the bottom of it or go stark raving mad ... one of the other

 

[JohnnyC]

Oh also ... didn’t see you mention it... but... did you change over your distributor cap?

 

[Fj moneypit]

The noise

 

[Fj moneypit]

I had a similar issue... happened mostly when it got warm/hot

Turned out to be my header to y-pipe was barely holding on ... slid out from its slip jointed and band clamped areas ... both sides on the y-pipe

When it got hot it would expand the header and push past the pipe

Exhaust leak

It was so slight but it was there... slid it back in and clamped it down hard... it was good for a day then it did it again

My muffler /back was pulling on the connection ... and when it got hot it would start to slide and separate again

Removed my entire system and made sure there was no tension pulling back... never happened again

Do not know if that is anything that you have going on... but... it’s a thought... things get hot and expand/move

Sure the header is seated correctly on the head? Maybe a crack on the header that separates when it warms up?

Just throwing that out there

Good luck... keep it up... you’ll get to the bottom of it or go stark raving mad ... one of the other

Header is brand new. The exhaust is welded so just connects to header then out the back thru the muffler. I did replace coil cap etc about a month or so ago. Wonder if it’s a coil spark issue. Just seems to happen when running though. Sounds like head gasket or exhaust to me but I check head gasket with block test

 

[Fj moneypit]

Gonna check exhaust flange again and a friend suggested using a scope to check for leak.