the story continues-v6 perhaps not firing on all cylinders

hogggman · Post by **hogggman** » Tue Mar 25, 2008 8:11 pm

hi all,
following on from the other thread about hydraulic lifters,it seems prudent to determine whether all 6 cylinders are firing,as suggested by several other bongo owners.on saturday i decided to remove and inspect the spark plugs.before removing each plug,i wanted to remove the plug cap and connect one of those bulb type testers that lights up whenyou fit it between the plug and the lead,then start the engine.i tried this but the tester ended up so far down,and so tight in the spark plug hole,that i couldn`t see whether it was lighting or not(that and i don`t think it actually fit onto the top of the plug)so then i plugged the tester into the plug lead and earthed it to the engine,and started it.every single plug lead caused the tester to light well,and then i removed every plug in turn,cleaned and`gapped`them,and did the same with them.all of them provided a good strong spark.they were all in good condition,with no carbon fouling,soot,oil or any other deposits.
as i was doing this,i would remove 1 plug at a time,and started the engine to check the engine sound and how it ran.strangely,on all but one plug,it didn`t noticeably change.with one particular plug removed,it ran very poorly,and almost stalled.with that plug connected and the others disconnected one at a time,it ran without noticeably changing.
until i checked this previously,i had no reason to believe that it wasn`t firing on all cylinders,apart from the tappetty noise it makes.it starts first time every time,never stalls,doesn`t chug,and reaches 80mph seemingly effortlessly(on a private road,of course)
i suppose the problem,if there is one,now that i`ve eliminated spark plugs/leads/coil etc,could be either:
compression problem on one or more cylinders,
or fuel blockage?
remember it had been standing for 10 months before i bought it.
any suggestions would be most welcome.i can borrow a compression tester from a friend-not that i know what it should be,but i`d compare all the other cylinders with a `known good one`
many thanks
jamie

Dolly1 · Post by **Dolly1** » Tue Mar 25, 2008 9:15 pm

Hi jamie,the process of elimination goes on,but you seem to be on the home straight now,i think you might have a compression problem which would make the valves sound a bit tappety,a compression gauge could help.perhaps you might be able to hire from a local garage? lionel

francophile1947 · Post by **francophile1947** » Tue Mar 25, 2008 9:23 pm

That's weird! - potentially 5 duff cylinders

A compression test is probably your best option here. If the readings show 5 low cylinders and it's burning oil, it would indicate worn rings/cylinder bores - if not, probably burnt exhaust valves/seats. Don't forget to remove all the HT leads before cranking engine over.
Have you tried injector cleaner yet?

hogggman · Post by **hogggman** » Tue Mar 25, 2008 9:27 pm

hi,
i have a friend who has a compression tester,so i should be able to borrow it.is there any easy cure for poor compression,an additive perhaps,or is it a major job,ie pistons/rings/rebore etc?
thanks
jamie

or even a broken con rod?never thought of that.surely that would wreck the bottom end though?
thanks

francophile1947 · Post by **francophile1947** » Tue Mar 25, 2008 9:44 pm

hogggman wrote: or even a broken con rod?never thought of that.surely that would wreck the bottom end though?
thanks

You have NOT got a broken conrod - your engine would be in bits.
You could try putting some Redex in each cylinder and leaving it overnight - this may release sticking piston rings. If you do that, place some rag over the plug holes before spinning the engine a few times, on the starter, to clear most of the Redex out - replace the spark plugs and fire her up - hide with embarrassment cos' you'll fill the neighbourhood with vast amounts of white smoke

Dolly1 · Post by **Dolly1** » Tue Mar 25, 2008 9:46 pm

hi, seeing as the bongo has been unused for 10 months it could just be sticking piston rings.Redex is the usual cure.Run the engine till working temp:remove plugs,pour a measure into each piston,leave overnite.Cover plug holes with clothes.crank the engine over to get rid of redex,replace plugs,fire up and proceed to create a huge smoke screen.hope this helps with your problem. lionel

francophile1947 · Post by **francophile1947** » Tue Mar 25, 2008 9:47 pm

Dolly1 wrote:hi, seeing as the bongo has been unused for 10 months it could just be sticking piston rings.Redex is the usual cure.Run the engine till working temp:remove plugs,pour a measure into each piston,leave overnite.Cover plug holes with clothes.crank the engine over to get rid of redex,replace plugs,fire up and proceed to create a huge smoke screen.hope this helps with your problem. lionel

Beat ya!!

Dolly1 · Post by **Dolly1** » Tue Mar 25, 2008 9:51 pm

hi john great minds think alike Regards lionel

The Great Pretender · Post by **The Great Pretender** » Tue Mar 25, 2008 10:20 pm

If the compression test shows low pressure on one or more cylinders squirt some redex in and test again, if still down it probably isnt rings look for a valve problem. Also injector/s could be giving poor spray patern or flow

apole · Post by **apole** » Tue Mar 25, 2008 10:37 pm

Just had a thought. Whilst mine was in for an LPG checkover, the garage lent me an old Saab 9000. When it first started and for the first few mins it made a noise very similar to a tappet, however they told me it was a petrol injector that was failing so that could be another explanation for the tappety noise.

Andy

hogggman · Post by **hogggman** » Tue Mar 25, 2008 10:53 pm

hi guys,
what type of redx shall i get?there`s fuel system cleaner and injector cleaner,amongst other.would wd40 do the same job?
thanks
jamie

hogggman · Post by **hogggman** » Tue Mar 25, 2008 10:53 pm

sorry,i meant redex

francophile1947 · Post by **francophile1947** » Tue Mar 25, 2008 11:01 pm

Have to confess I didn't even know there was more than one Redex

It was Upper Cylinder Lubricant when I last used it, but probably the Fuel System cleaner would work. I believe WD40 would be useless for the job.

Dolly1 · Post by **Dolly1** » Tue Mar 25, 2008 11:03 pm

Hi Jamie,Redex petrol treatment,not wd40 that stuff would run past your pistons and dilute the oil in the sumpl Regards lionel

dandywarhol · Post by **dandywarhol** » Wed Mar 26, 2008 2:09 am

francophile1947 wrote:That's weird! - potentially 5 duff cylinders
A compression test is probably your best option here. If the readings show 5 low cylinders and it's burning oil, it would indicate worn rings/cylinder bores - if not, probably burnt exhaust valves/seats. Don't forget to remove all the HT leads before cranking engine over.
Have you tried injector cleaner yet?

A lot of CDI ignition doesn't like the plug leads not earthing and can damage the ignition unit.............

the story continues-v6 perhaps not firing on all cylinders

the story continues-v6 perhaps not firing on all cylinders

v6 engine