Hi,
I got the details of the leakage test wrong. Here's what they did:
Head off, pour some liquid onto the pistons, wait for it to drain through. No pressurising, just gravity.
They say that some cars, even old ones, hold the liquid for days or weeks. Apparently it's not a test which all cars fail.
It seems I'm stuck between a rock and a hard place. If I have the work done (basically a complete engine rebuild) I have a good engine which will almost certainly outlive the car. If I don't have it done, they have advised me that it needs doing, and it's on my head if it goes wrong. Then I end up paying for two head gasket jobs.
Interesting that no one I have spoken to about this (which includes the AA) has ever heard of this type of leakage test. I wonder whether it's really proving anything. Any of you heard of it before?
Cheers,
Mark
|
Mark
Pressurised or not this test depends entirely on what 'liquid' is used. As the head is off have you been able to check the condition of the bores? Only if they are showing negligible wear would a ring change be advisable - if they are worn it's really time for a rebore and pistons.
The fact remains that changing a head gasket, even with a small leak, won't put any more stress on the piston rings, and the garage is completely wrong to suggest it will.
If you're satisfied the engine ran well and didn't burn oil, you're probably OK to ignore the rings, but you're the only one who can make that judgement.
Regards
john S
|
Nope! Never heard of it done this way!
Sounds a bit Heath Robinson to me.
I'd only take readings from a compression test, nothing else.
Just have it put back together and all should be well.
--
groups.msn.com/honestjohn - Pictures say a thousand words.....
Reply |
Report as offensive
| Link
|
Thanks all for your input. I have also spoken to a number of garages, engine rebuilders, enthusiasts and even a guy who works exclusively on these engines. Without exception everyone thinks that the price is ludicrous and that the diagnosis is "questionable" at best.
So I have lost confidence in this garage, and will be making alternative arrangements. I'm currently trying to think of a way of telling them this, considering that they have my car, and in a large number of pieces at that.
Thanks all
Mark (rather stressed and considering buying a push bike)
|
Piston rings have a split in them which allows them to be opened when they are fitted to the pistons. The two ends will have a small gap between them once the piston is fitted (the engine specs in Haynes give this gap as 0.25 to 0.50mm depending on which of the three rings it is). The piston ring groove also has a clearance to the ring of 0.05 to 0.09mm.
So, depending on what fluid is poured into the bores, it is almost certain to drain into the sump at some rate or other. The gas tight seal you need when the engine is running is provided by a very thin oil film as the rings are pushed down and outwards on the compression stroke. Even so this seal isn't totally 100%.
I would not trust this test. Only test to trust is a proper compression test carried out on a warm engine just after shutdown.
Have you been able to look at the condition of the cams and the cam housing whilst it's in bits. I have the same engine as you (in an 820 VS) and the inside of my cam covers is spotless, with no wear on the cam lobes visible to the naked eye. this on a 130k motor. What this tells me is that the previous owner changed the oil frequently and used good stuff (I also know this because he's a long standing family friend and is a car nut too). More importantly i take this good news as an indication of the general state of the rest of the engine (especially the turbo bearings) in addition to other factors (performance against the clock, no oil burning, good starting etc etc). The overhead cam area is prone to sludging up on a poorly looked after engine, 'cos it's the area that gets hot last and has the least oil feed.
So, look at the cam area of your motor, along with the condition of the bores. You should still be able to discern some honing marks and might just be able to feel a very slight ridge with your thumb nail where the top ring reaches. If all appears well here and around the cam, then I would say it is unlikely you need new rings.
Pay the garage for the work they have done and find somewhere else to do the rest. Phone around and find somewhere before imparting the good news to the garage, not everywhere wants to do half a job.
|
|
|
You may find it hard to get another garage to finish off the job
as most do not like putting others problems right.I would let them finish the job as they did say it was up to you whether you had the work done so I would just say to them I`ll risk it
bearing in mind as it is in bits you will have to pay for recovery from one garage to another.unless you tow it yourself
or get someone else to do it that you know.As the other posts have said I have never heard of ring testing done in that manor.but then if rings are worn you normally burn oil all the time.
|
Hi,
I think I have found an engine reconditioner near me who will take on the work. I am prepared for some trouble when it comes to the current garage billing for the work they've done, but I really don't think there is a choice because their quote is £1000 more than anywhere else. The more I investigate, the more it seems just to be a number plucked out of the air. Everyone else's estimates and quotes are at least in the same region and theirs is double anyone else's.
It's up to me whether I have the work done, but if it needs doing it needs doing. My objection is playing twice as much to have it done as it is worth.
I'll just have to pay for recovery and be done with it. It's not ideal but there is really no sensible alternative.
Thanks very much for everyone's help!
Mark
|
So you're just going to have the cylinder head refitted, with a new gasket and a dollop of sealant* around the oilway then?
*Loctite 574 works well here, believe me.
--
groups.msn.com/honestjohn - Pictures say a thousand words.....
Reply |
Report as offensive
| Link
|
|
|
|
How much do they want for doing the head gasket?
|
I am waiting for a quote for head gasket only. Previously they wouldn't be tied to a price in case more work was required. This may be a little dodgy - why not quote for the simple job with the proviso that this is only for that job? But anyway...
The written quote from the engine rebuilder (when I got it) was avtually double his original phone price. Considering the cost and hassle of moving the car, it would hardly save me anything.
I think I will either get the original garage to do the whole job (even though their labour time of 30 hours is totally rediculous and they won't negotiate) or get them to put the head back on and take my luck, depending on the costs.
Not at all happy with it as the absolutely unanimous opinion is that they are taking the micky with their job time, but I am basically snookered.
I'll keep you posted...
-Mark
|
No sooner had I written that than...
Putting the head back on (new gaskets (obviously), lapping the valves in, new valve stem oil seals, new belts and tensioner, oil, filter, coolant: £643
The above plus new piston rings: £1673
£1030 extra for piston rings which no one else thinks I need.
Anyone got any words of wisdom before I tell them to just put the head back on?
Thanks,
Mark
|
>>Anyone got any words of wisdom before I tell them to just put the head back on?
Yes, don't darken the door step of that particular garage again.
|
|
|
|
|
|
If the garage do the work they originally quoted you for replacing the piston rings won't involve taking the head off again (unless the bores require work).
Rings are usually replaced by dropping the sump and removing each piston/con-rod in turn and replacing the rings.
Highly improbable that worn rings would affect the work done by the garage, in the event of any future problems, i.e. headgasket failure they would have to prove that the rings caused the failure and not their faulty workmanship.
Sorry that you're committed to this garage as they sound a bit wild west to me.
|
Hi Malcolm,
Thanks for the comments. Far from being Wild West I think the garage are completely overkill. They want it to be perfect, like the day it left the factory. That's simply not an economically sensible approach on a nine year old car.
I understand pistons can be withdrawn from below, but I believe it is (to all intents and purposes) necessary to rehone the bores when you replace piston rings. Can this rehoning be done from below?
If it can, that completely solves my problems - I can do the work at a later date. In fact they were a bit naughty not to tell me this. All assuming it can be done from below, of course.
By the way, they are suggesting that the head repairs (specifically relapping the valves) will increase compression back to its original level, and this will excentuate any hidden problem with the rings. So they're saying the head will blow the rings and not the other way round.
Regarding having to prove anything, in my experience the burden on proof is 100% on the customer, and not at all with the garage. They (not talking about one garage in particular here) simply deny responsibility and as a customer there is absolutely nothing you can do about it.
Thanks for your input! Appreciate it all!
-Mark
|
Mark
If you do have to go for the new rings later it is a head-off job, I'm afraid. Pistons will be usually be withdrawn from the top, and the honing would certainly be done from the top.
It's often said a valve job on an old engine causes problems. However, unless the valves are really bad, it won't greatly increase combustion pressures, and those depend anyway on your right foot. So, drive it sensibly and you'll be OK. It's where the boy racers do a valve job, and then proceed to thrash the engine that problems occur.
Regards
John S
|
Hi John,
Bit worrying that you say a heavy right foot can cause problems after a valve job. I don't drive hard or fast generally, and I certainly don't rag it on anything like a regular basis, but it is a fast car and I do put my foot down sometimes. No point having it otherwise... I was considering going on some track days.
Well if it has to be redone it has to be redone. I will take it elsewhere and have it redone for only about the same as the £1030 I'm saving by not having it done now, so no worse off.
Cheers,
Mark
|
Mark
Bit late but here goes. Don't worry - I was talking about the max power brigade with a worn out car who thrash it everywhere. That said a track day gives even a new motor a hard time, so no guarantees there! I reckon it will be fine.
Regards
John S
|
|
|
|
I'm not familiar with the Rover engine but I would imagine the crankshaft would have to be removed to get the pistons out??. This would involve quite alot of extra work removing clutch gearbox etc. Also while the crankshafts off it would be false economy not to have it checked/reground and new shells fitted. I think if you were going this far it might be cheaper having a fully reconditioned guaranteed engine or new Rover short engine fitted.
Unfortunately the garage don't seem to have done a proper compression test before removing the head so their is no way of knowing if lapping in the valves will cause any problems. By advising you of the potential ring problem now, they are covering their backs if the car smokes when they get it all put back together. They want you to pay for any remedial action not them.
imo If the oil consumption was low and you didn't notice any oil fumes/piston slap noises, I would just go for the head recon and hope for the best. You could spend £1000 now having the rings done and find the big ends are knocking 6 months later. All depends on how highly you value the car and what it's going to be used for which way you go.
|
|
|
|
|
|
|
