26 replies to this topic

[ACDodd]

Leaving this one to 'if it aint broke don't fix it routine will end up burning the valve seats more and possibly cracking the head. A compression test has highlighted an issue.fix it now before it does further damage.

Ac

Edited by ACDodd, 07 August 2018 - 04:56 PM.

[croc7]

If giving the cylinder bores a squirt oil increased the compression check figures, wouldn’t that point to a worn piston/bore rather than valves??

[happydude2012]

well im going to take ACs advice and get the valves re-seated, but i dont think theres a major issue here with pistons - im a noob i guess and even im confident to say that having been reading a shed load over the last week or so on this topic.

Been reading around this and id not really warm her up properly on the first test - second test was more like operating temp, so with the higher pressure of 180 with oil, dropping to an even 140 once warmed up and how it should be, 4 complete passes of each cylinder the pressure was 140psi (ish)  - i dont think pistons or piston rings are an issue, i truly dont - perhaps a worn ring in 3, but ill check that out with the head off. 

The car is not symptomatic of worn/damaged pistons or rings and was fully rebuilt 3 years ago and doesnt get raced or rallied - ive looked after her and i dont think theres a  significant issue apart from as AC said, as pert of a maintenance run getting the valves cleaned up.

 

my issue is this tapping, which also may, once the valves seats get looked at be resolved - so once i finally get this DTI, im going to check the cam lobes, and if thats ok, the only thing left that it can be is;

 

1) Valves sticking? not seating properly.

2) Rocker - either flat spot on roller or shaft wear  (which i dont think its is)

3) Cam follower (most likely scenario given the symptoms)

4) Cam lobe wear (second most likely given the symptoms)

 

and that, for what its worth, is my humble opinion on it. 

Edited by happydude2012, 08 August 2018 - 07:07 AM.

[Bat]

Hi,

Number 1 would cause both your noise and the wonky readings. Cylinder 3 with the highest reading is where they should all be I think.

Once the valves are out check the guides for wear otherwise anything else will be a waste of time...

Look at the back of the valve heads for uneven deposits to give you a clue.

Cheers 

[happydude2012]

well ill cerainly check it out - thanks for the tip, might as well with the head off anyway.

the readings arent wonky at operating temp - cold engine readings are inaccurate according to what ive discovered, i can see at start up the 140 in 3 might raise suspicions as the others were 120, but when running warm the readings are all 140 (ish) with more than  1-2% difference - am i way off in my thinking?

 

Ill have the head looked at and the pistons too - and then we will see

[happydude2012]

well, im throwing the towel in.

Had enough now.

 

Dial test indicator that arrived is metric - couldn't get a reading off the back of the rockers as when they lift of course they move forward so indicator is all over the shop with inaccurate readings

Took the rockers off to get a reading off the push rod in a more vertical way, with a bit of stiff metal across the cup of the pushrod, and frankly i dont know whats right and wrong anymore.

I note that on rocker one there is almost a full rotations difference in the guage at full lift, all the others are 7 full rotations plus a bit and number 1 is 6 full rotations and a little bit,- does that mean the cam lobe is naffed up? honestly i had such a hard time finding somewhere decent to magnetize this thing to and hold steady, i dont know whats accurate and whats not so im retiring.

So thats that, end of the month, me pals having it and stripping down the engine - cant be bothered anymore, going to do more harm than good.

Edited by happydude2012, 08 August 2018 - 05:44 PM.

[ACDodd]

I rest my case worn cam and follower.
Think about rocker ratio and cam combination when you rebuild.
Also all those that answered this thread. Diagnosis is about checking and testing, not guessing and hoping.

Ac

Edited by ACDodd, 08 August 2018 - 07:28 PM.

[Bat]

Hi,

Just stick the end of the DTI in the top of the pushrod that's how I measured for cam timing.

Cheers 

[sonikk4]

I would seriously listen to ACDodd after all he does this sort of a thing for living, just saying like.

[happydude2012]

I rest my case worn cam and follower.
Think about rocker ratio and cam combination when you rebuild.
Also all those that answered this thread. Diagnosis is about checking and testing, not guessing and hoping.

Ac

 

As suspected i believe you are quite correct - i honestly cant think of anything else it could be.

Was always going to take your advice AC -No worries.

 

So my plan is thus:

end of the month, engine out, stripped to bits and everything checked.

Head will be attended to, valves reseated and checked.

 

suggestions for cam and rocker appreciated - the swiftune i have fitted is set as per the correct specs for that cam, 1:5:1 and the sw5 - ill be honest and say ive not had any issues until now but take your experience onboard with 1:5:1 rockers causing cam wear, im not doing a full rebuild every 3 years.

 

so until end of month - im walking away from this and doing some more research.

[happydude2012]

Hi,

Just stick the end of the DTI in the top of the pushrod that's how I measured for cam timing.

Cheers 

thats what i did bat - the first pushrod was a full revolution less than the others - so cam and follower seems to be the issue on this cyclinder.

[happydude2012]

I would seriously listen to ACDodd after all he does this sort of a thing for living, just saying like.

i am sonikk4 - been talking to AC alot PM. thanks