Whump, whump, whump from intake...?

[westcoaster]

So, there I was teaching my 9 year old daughter to drive...

She didn't quite have the feel for the fuel and reved the engine. After I noticed this "whump" sound coming from the intake. I figured she may have bent an intake valve as the engine wasn't quite up to full operating temp just yet but had been operated at slow speed for at least 5-10 minutes.

It was quite a noticable and distinctive "dead cylinder" sound but with no real noticable loss of power or vibration.


Since we were out long way from home I simply ran the engine for the rest of the week sometimes really ragging on it.

Got home last night, dropped the boat off, on my way back engine tone changed and whump went away!


Only thing I can think of was a stuck hydraulic lifter.... Why? what to do to pervent it from happening again? Common problem?


MF block 1.6 td stuffed into an '87 samurai. The samurai was flat towed to and from the camp spot. Mostly used to crawl around the bush with long up and down hill driving.

[colhel59]

to me it almost sounds like the turbo is giving the engine more air than it can take in. was the engine boosting any and do you have any intake on it, ie cone filter my two cents
Colton

[westcoaster]

No, I don't think so...

"whump" would increase and decrease in frequency with engine RPM's (like a dead cylinder would)
I could still hear boost when stepping on the fuel. (turbo spooling up, blow of valve in place and in an operational state but not venting)
Sound was happening all the time, even at idle.
Yes, the intake I have did attenuate the noise considerably. Pull the intake plumbing from the samurai air cleaner off the turbo and the sound is reduced considerably but still there.

I figure the only thing it could possibly be since it corrected itself would have been a stuck lifter. Even then one would have thought an intake valve stuck open would have contacted a piston...?

[Mark(The Miser)UK]

Temporarily dysfunctional injector.... A lazy cam follower won't repair itself as far as I know, unless that is a blockage issue....

[wolf_walker]

Diesel Purge and drive the snot out of it, if you are doing a lot of low speed off-road crawling, un-good things will eventually happen.  Need to get some loaded RPM on these things now and again to keep em happy in my observation.

[8v-of-fury]

I second a sticky Injector, as a stuck open valve would have grenaded the engine by now.

A diesel purge, and 4000+ rpm for about 35 seconds does wonders.

[westcoaster]

Hummmm....

They were rebuilt not that long ago by Giles shop.... 8000km?

If it was a stuck injector why would the noise be coming out the intake?


Ok, injector cleaner it is, and believe me, I have ratbagged it enough even while it was whumping....