Piston down (compression)

[RedRunner]

Hi all...

I wonder if any other 3.0 V6 owners have had this problem. If so, how did you sort it?

My runner (1994 UK 4Runner 3.0L V6 Petrol 3vze) runs on LPG, and has done for the most part of her life, I only recently bought her (97K on the clock), the head gaskett was done on the recall last year with Toyota.

I took her in to a LPGA certified, and reputable garage for a service for a filter change (as was advised by Sancho.....(thnx)) and the guy said he could hear/feel a regular missfire or inconsistency in the firing order, so he tested it for me using some nifty voltage drop sensor (looked impressive), and it showed that one of my cylinders has no compression (almost).

However as he did not charge me for this service, hence he did not delve deeper to find out which cylinder it was.

.............................. .............................. .............................. ..............

My solution would be to replace the entire cylinder head on both sides, is this nessasary?

Also is this going to be as easy as it sounds?

I'm a mechanically minded person, and can confidently replace most parts on vehicles, however, ive never really dug this deep in to the inner workings of an engine before.

The guy said that i was talking 3 figures for him to do it.

Any advice please, as im just about to spend money on cosmetics, and body lifts, and winches, and...and...and...

Is my engine fried??? I feel like ive had me pants pulled down buying her now, i payed 2700 for her 2 months ago, dont think ive ever loved anything as much

[RedRunner]

oh yeah...

sory my post is a bit long guys, but i appreciate your time.

[NiftyNev]

so he tested it for me using some nifty voltage drop sensor (looked impressive), and it showed that one of my cylinders has no compression (almost).

Huh! You've confused me and i think the guy has baffled you with bullsh!t. Compression can only be tested with a compression tester. You should have gotten a list of compression figures for each cylinder. Did he remove the spark plugs?

Nev

[warby]

it may be valve or worn piston rings.
as for replacing both cyl heads your just throwing money away.
i'd start by buying yourself a compression tester about £20-£30 from most
motor factors.
follow the tool's instructions , or any car's manual on how to do a compression test.
depending on what tool you buy you may need someone to crank the engine
while you do the test .
if your quite handy with the spanners you should find it a doddel.

1. dissconect the coil's HT lead. (engine wont start then)
2.remove spark plug no1 cyl install the tester get 2nd man to crank the
engine while you make a note of the readings ,1st crank,& peak pressure.
stop cranking.
3.reset the tester & repeat on the other 5 cylinder's.
4.compair the results of all 6 cyl's, they should all be roughly the same if 1
cyl is way down put a teaspoon of engine oil down the plug hole & retest that
1, if the reading goes up it's ring's if it stays the same it's a valve. if the readings are low on 2 ajoning cyl's it may be a head gasket.

hopefully the copression is up on all the cyl's & the littel missfire is just a
poxy plug or HT lead.

you say your surf's LPG makesure gas is off & the engine's warmed up prior testing.

hope this may be of help (WARBY).

p.s you can allway's go to another garage for a 2nd oppinion.




life is like a pube on a toilet seat now & again you get ####ed off!!!!!!!!!.

[RedRunner]

Huh! You've confused me and i think the guy has baffled you with bullsh!t. Compression can only be tested with a compression tester. You should have gotten a list of compression figures for each cylinder. Did he remove the spark plugs?

Nev

I know what you mean, Nev, i've had trouble explaining this to people myself. I've never heard of it before, and its not accurate, but it does measure a consistent voltage drop with each power stroke (each piston). The machine had Vauxhall written on it. It doesn't give pressure readings or values, it just compares one voltage drop with the next, and he did say that i would need to do a compression test to get to the bottom of it.

+ i am a sceptic and am not sold bullshit easily, so i believe him, + he went through allot of trouble explaining this to me and showing me just what had done.

spark plugs were not removed, this was done with the engine running.

[RedRunner]

Warnby!!


Thanks a lot mate, i think thats exactly what i will do. Sounds logical.

Was thinking though, that the head gasket is still under warranty, (dunno if i mentioned), would there be any use in taking it in to toyota to shout at them?

Or should i just isolate the problem personally before the remaining moth of warranty runs out on the gasket....

[Sancho]

First question: Does it run OK on petrol?
Second question: Did Toyota only change one HG or both?

It does sound like when PDR had one of his HGs go but the LPG makes things a bit more complicated.

[Hilux]

Hi where did you buy it from was it a dealer as you get 3months or 3000miles warranty, you say you have only had it 2months. What colour is the vehicle is it standard as we might know it from on this forum and be able to give you more info on it.

[stevo]

valve burn

Toyota petrol valve seats made from chocolate, very susceptible to erosion when run on lpg, usually wear to the point of no valve clearance. Check tappet clearence if no clearance then you have worn valve seats, quick fix re-shim tappets to get right clearance, if keeping long term on lpg then you need to get hard valve seats fitted to cyl heads, which we have done before for site members.
Cheers, Steve.

[Albannach]

I know what you mean, Nev, i've had trouble explaining this to people myself. I've never heard of it before, and its not accurate, but it does measure a consistent voltage drop with each power stroke (each piston). The machine had Vauxhall written on it. It doesn't give pressure readings or values, it just compares one voltage drop with the next, and he did say that i would need to do a compression test to get to the bottom of it.

+ i am a sceptic and am not sold bullshit easily, so i believe him, + he went through allot of trouble explaining this to me and showing me just what had done.

spark plugs were not removed, this was done with the engine running.

Sorry, but I'm with Nev. You're being bullshitted.

There's no way to tell if a cylinder is down on power/compression without at least a compression test. Ask him exactly what voltage drops to make him think a cylinder is suspect.

[RedRunner]

Sorry, but I'm with Nev. You're being bullshitted.

There's no way to tell if a cylinder is down on power/compression without at least a compression test. Ask him exactly what voltage drops to make him think a cylinder is suspect.

Hi,

http://www.freepatentsonline.com/4126037.html

take a look at this, theres not much info there it is a patent, but there is more info out there i will look further and post when i understand a bit more, as im not willing to defend something i don't really get.

but i'm convinced its possible.

[RedRunner]

First question: Does it run OK on petrol?
Second question: Did Toyota only change one HG or both?

It does sound like when PDR had one of his HGs go but the LPG makes things a bit more complicated.

Not sure bout toyota, but i just assumed that as it was done on the recall, they would have changed them both, as they were crap from manufacture.

(am assuming you know that toyota recalled all of these engines for faulty head gaskets)

It seems to be doing the same thing on petrol mate, not really much difference at all.

Ive just ordered a compression test kit, should be with me next week.
I'll post the results as soon as i get them.

[RedRunner]

Hilux;

Red Toyota 4 Runner (uk)

3.0L V6 Petrol (obviously)

Bought it from a place called sleaford between Lincoln and peterborough.

Private sale.

really nice guy, as seemingly genuine as one could wish when buying a used car privately.

See picture at bottom of post.

Stevo;

nice one mate, i think most likely its gonna be one of the valves, as that seems to be where everybody is pointing the blame.

i'll look in to finding some hard valve seats, as am a student at the mo, and couldn't even imagine having to run her on petrol full time. it brakes my heart paying that much for fuel, but at the same time love the car too much to consider getting rid.

[Sancho]

Hilux;

Red Toyota 4 Runner (uk)

3.0L V6 Petrol (obviously)

Bought it from a place called sleaford between Lincoln and peterborough.

Private sale.

really nice guy, as seemingly genuine as one could wish when buying a used car privately.

See picture at bottom of post.

Stevo;

nice one mate, i think most likely its gonna be one of the valves, as that seems to be where everybody is pointing the blame.

i'll look in to finding some hard valve seats, as am a student at the mo, and couldn't even imagine having to run her on petrol full time. it brakes my heart paying that much for fuel, but at the same time love the car too much to consider getting rid.

Well, Stevo is in Stockport, not a million miles from you and comes very highly recommended for sorting out any surf problems. Take it to him and everything will be sorted, properly.

[BUSHWHACKER]

Blimey, a student that can afford to run a V6!!!


Cool tho.