Low compression on V8

[ManxNeil]

After seven years' ownership and 82,000 enjoyable miles the engine on my 4.2SE has just effectively been condemned. The car was five years old and had exactly 25K miles with FSH when I bought it, so it's a 2003 and has a total of 107,000 miles now. It's been maintained through all its life - annual services and repairs as required all done professionally by a Jag-trained independent.

Earlier this year the engine warning light (MIL?) started to come on and the codes revealed specific faults which were addressed, only for the light to come back on soon, sometimes within 24 hours of the fault being cleared. Performance and reliability of the car was, and remains, seemingly unaffected (touch wood) though in the last month or so a puff of blue smoke, which clears immediately, can be seen on start up. I don't consider the oil consumption particularly excessive for a car this age - maybe a pint every six months/5,000 miles, if that. I took the car to the local Jaguar service agent for a compression test which revealed four of the cylinders low and that the problem lay in the cylinders themselves rather than the valve gear. The low cylinders read 130, 120, 90 and 75 when they should be 150. They were spread around, so it isn't a problem with one block or row. They said that the low compression was affecting the operation of the MAP sensor and it was this which was throwing up the various apparent faults.

The question now is what to do. Unfortunately I'm very attached to the XJ, loving the V8 power, early-model looks with all the chrome and the (comparatively rare) Jaguar Racing Green finish. In fact, I'd not long had some minor corrosion issues at the rear of the car addressed, including a resprayed boot lid, so it still looks fabulous. My plan is to continue the run the car 'as is' for the time being until smoke or oil consumption start to manifest themselves a bit more, but then what?

I can't say the car owes me any money, I bought it at the right price back in 2008, but I may be vulnerable to my heart ruling my head and looking at a reconditioned engine rather than scrapping the thing and stripping it for parts. The local agent has advised allowing £7,000-£8,000 for obtaining and fitting a Jag-approved recon unit, twice what the car is probably worth. A rebuild with a rebore/sleeving etc. could prove nearly as expensive. Here on the Isle of Man options are limited and it's likely I'd have to take the XJ to the UK for anything that might be more cost effective. Though I do all the work on my classics (Mk2 Jag and SIIA Land Rover) the complexity and electronics of the X350 are too rich for my blood.

Any opinions would be of interest!

[J44EAG]

Very unusual indeed to hear of a steel lined 4 litre or 4.2 to be suffering low compressions, Neil. Short journey and attendant ring wear are the most obvious causes and symptoms. The cylinder bores may or may not be worn. Only stripping will reveal the true extent of the wear and to which internal parts of the unit.

So the car has an issue which now needs resolving. Perhaps consider a good known condition second hand engine from a reputable breaker such as Eurojag. That is likely to be the most cost effective solution. May be your local repair guys could undertake a motor swap for you. This would largely entail mechanical work rather than electronic unit investigation. After all, an electronic set up will remain as original and not be able to detect the change of an engine block. Once any fault codes have been cleared, it should be all systems go again.

http://www.eurojag.com/jaguar-engines-c ... p-916.html
Racing Green Cars in Guildford have been rebuilding V8 motors for several years now. They can provide crank and bearing services and possibly ring/bore kits. Perhaps worth giving a call for further advice. There is a fair amount of stripping involved to recondition an engine and when parts and labour are factored into any repair equation, rebuilding probably comes in a very bad second place compared to swapping out a worn engine and replacing with either a new or second hand unit.

Market value of the car needs to be factored also. I`ve been looking at X350R models on line recently. There is a 2003 XJR on ebay near Gatwick presently with 119K miles described as a good usable car for £5500 although I gain the impression that the owner will accept £5000. Non supercharged cars seem to be priced at appreciably lower prices.

I might be tempted if I were in a situation with a worn engine to cut my losses and part exchange the car for a newer model and alleviate the pain of owning a vehicle which is likely only to deteriorate further. In other words, move the car on under its own steam before it comes to a complete halt and is then valueless.

I would like to say "I hope that helps" but I doubt in this case that that would pan out.

Mike K

[Brakebuster]

as above

you have the usual dilemma , continue with investigation and spend money on finding the engine is no longer serviceable

or buy a replacement engine and go with that regardless

tough one

BB

[ptjs1]

Neil,

Sorry to hear of the problems. As you've realised, it doesn't make economic sense to put a new engine in, especially if the car is usually running fine and can be sold on / px'd.

If it's not stuck valves, then it could seem to be piston/ bore wear or maybe stuck rings.

If it were me. I'd throw some additives in the engine. Start with one that can address stuck piston rings. After that, you could do worse than try some Ametech (Quintin Willson favourite) and see if that addresses piston / bore wear. A cheap plan that might just work!

Good luck

Paul

[robv12]

this is the first problem I have heard of with a 4.2V8 at this mileage, as you all know ALL of my 350's are high mileage, the largest distance covered being 270K, all with out issue except my chipped and tuned XJR and the infernal devil juice car and both of these are/were 160K plus

The 4.2 is so under-stressed that it is considered to be bomb proof

so options??

I think they are all covered above

But my choice would be a used unit from EuroJag, they have rows and rows of them, they would be glad to see the back of some of them I reckon

Get the engine shipped to XJK in Stoke, one of the clubs technical supporters, get the car over there, spend a day and night in Stoke (such fun!!!), and drive it back after the engine swap which will take no more than half a day, a day at most if there are any snags

XJK had the engine out of my 350R THREE times, Ian had it down to an hour and twenty minutes in the end

They are all ex Jaguar racing, have the right kit and a sympathy and understanding of our cars, especially 350 as Ian was the Global Training Manager on the cars when they were current, a good guy to get to know

[steve_m]

After seven years' ownership and 82,000 enjoyable miles the engine on my 4.2SE has just effectively been condemned. The car was five years old and had exactly 25K miles with FSH when I bought it, so it's a 2003 and has a total of 107,000 miles now. It's been maintained through all its life - annual services and repairs as required all done professionally by a Jag-trained independent.

Earlier this year the engine warning light (MIL?) started to come on and the codes revealed specific faults which were addressed, only for the light to come back on soon, sometimes within 24 hours of the fault being cleared. Performance and reliability of the car was, and remains, seemingly unaffected (touch wood) though in the last month or so a puff of blue smoke, which clears immediately, can be seen on start up. I don't consider the oil consumption particularly excessive for a car this age - maybe a pint every six months/5,000 miles, if that. I took the car to the local Jaguar service agent for a compression test which revealed four of the cylinders low and that the problem lay in the cylinders themselves rather than the valve gear. The low cylinders read 130, 120, 90 and 75 when they should be 150. They were spread around, so it isn't a problem with one block or row. They said that the low compression was affecting the operation of the MAP sensor and it was this which was throwing up the various apparent faults.

The question now is what to do. Unfortunately I'm very attached to the XJ, loving the V8 power, early-model looks with all the chrome and the (comparatively rare) Jaguar Racing Green finish. In fact, I'd not long had some minor corrosion issues at the rear of the car addressed, including a resprayed boot lid, so it still looks fabulous. My plan is to continue the run the car 'as is' for the time being until smoke or oil consumption start to manifest themselves a bit more, but then what?

I can't say the car owes me any money, I bought it at the right price back in 2008, but I may be vulnerable to my heart ruling my head and looking at a reconditioned engine rather than scrapping the thing and stripping it for parts. The local agent has advised allowing £7,000-£8,000 for obtaining and fitting a Jag-approved recon unit, twice what the car is probably worth. A rebuild with a rebore/sleeving etc. could prove nearly as expensive. Here on the Isle of Man options are limited and it's likely I'd have to take the XJ to the UK for anything that might be more cost effective. Though I do all the work on my classics (Mk2 Jag and SIIA Land Rover) the complexity and electronics of the X350 are too rich for my blood.

Any opinions would be of interest!

It doesn't matter what the car is worth; if you love it and can afford it then give it a new heart.
If you just like the style, comfort and it doesn't owe you any money then part it out and get another one.
if you are not sure then read Pet Semetary!

[ManxNeil]

Thanks for all those, gentlemen.

Mike - I think you've hit the nail on the head with your reference to short journeys. Living on an island 30 miles long by 11 miles wide means that short runs are the norm. I take the car over the to the UK only about three or four times a year which, obviously, is when it gets its only long blasts on motorways.

Market value is a consideration, I suppose. However, as I've indicated above, I'm very attached to the car and have spent money to keep it in good condition. If pushed, I'd probably want a replacement to be a relatively low mileage X358 and a brief look on Autotrader indicates good examples are still north of £17K. I could do this, but don't really think I want to chop the current car in quite yet. With no 'other half' urging the need for a 'sensible' car and no kids needing ferrying around, plus my old Land Rover (or even the Mk2 Jag) being able to step in as a backup car when required, there's a case - in my mind, anyway - of treating the X350 as another hobby car and spending the money on it. After all, how else are some of these going to survive into full-blown classic-hood?

Paul - Thanks for the reference to Ametech, I'd never heard of it. If the problem lies with the bores rather than the piston rings then it might be a short-term way of bringing the compression back up and getting the MAP sensor working properly again until another engine goes in.

Rob - I'm grateful to you and Mike for the Eurojag recommendation and I'll ring XJK to discuss the situation. It's not clear whether the engine would be supplied on an exchange basis but once any engine swap was done I'd like to get the original engine shipped back to my workshop so I could examine the block at leisure.

Steve - As you'll have seen above, the heart transplant is on the cards, but isn't Pet Semetary a horror story?

Cheers,

[J44EAG]

Cold starts, fuel wash and short journeys where engine temperature remains low are very destructive indeed. It takes something like thirty miles of hot running to neutralise the effects of oil contamination for each and every cold engine start. Some members may recall the article I wrote around five years ago in the magazine which explored the subject of oil degradation. It was entitled `The problem with oil` and was checked and sub edited by Mike Horlor.

The recommendation that cars used for short journeys should have oil change more frequently than those used for long journeys would appear to be a sound one. Typical signs of low temperature running usually show as condensation mayonnaise on the underside of the oil filler cap. Oil should be changed immediately that situation is recognised.

Paul and I had a phone call together regarding this low compression issue last week and Ametech additive came up for discussion. I understand from the Ametech site that the principle of the treatment is to attempt to restore compression buy molecularly coating cylinder bore and piston rings with a lead/copper substance which is claimed to fill marks and scores with the substance which is forced into defects and solidifies under compression......Mnnn. If only it was that easy to rebuild or restore a metal surface which has been worn away by sheering action due to an oil break down issue. That said though, it might be worth trying a couple of cans of the additive. If it does improve compression even for a short period, then that must be worth a shot. On line discussion on the subject and user reviews and benefits draw a mixed bag of opinion.

As regards the possibility of rings being held in piston grooves and therefore not being able to expand sufficiently against cylinder walls, that could be possible but I would have thought unlikely due to the enhanced nature of modern oils and their resistance to burning and detergent effects which tend to keep carbon in suspension rather than allow it to form on rings and lands. Old old type oils and their chemical simplicity were more prone to that sort of problem.

With the advent of the 4.2 engine which was derived from the earlier 4.0, an improved design of piston was incorporated in an attempt to reduce bore issues which although when steel (After Nikasil) could still give rise to some very occasional issues. The 4.2 pistons were of the forged variety and had additional oil holes incorporated to increase and maintain bore lubrication. Fuel atomisation, economy, performance and emissions also improved when Jaguar fitted 12 hole injector nozzles to the 4.2 (Six in the 4.0) which in theory and hopefully in practice helped reduce fuel wash within cylinders during the warm up period.

i believe keeping fuel injection components in tip top condition goes a long way to ensuring that an engine enjoys a long life. I regularly dose fuel with a variety of cleaners. I use Cataclean, Seafoam and other propitiatory injector cleaners in an attempt to ensure that fuel is continued to be pumped into my engine in a controlled mist rather than in globular form which can occur if injector nozzles become blocked. Globular formation certainly won`t help cylinder longevity.

Seafoam can also be used in engine oil and is claimed to help loosen and disperse carbon deposits which can form on internal engine components. Such additives may take some time to do their work and might take up to a month or so before any effect becomes noticeable. Results through use of these chemicals are not guaranteed but if an improvement does occur, then it is money well spent. Before using internal engine additives, you should ensure they will not damage catalytic converters or affect oil viscosity or lubrication qualities.

As I understand it, most breakers will supply a bare core engine devoid of ancillary equipment within the price they quote in their advertising. Any specific additional parts you might need are usually left on an a replacement engine but additional charges will apply. Most core engines are supplied on an outright purchase basis rather than on exchange.

Hope that helps.

Mike

[ManxNeil]

Thanks, Mike, that's a lot of food for thought.

Oil has been changed at annual/10,000 mile services only. In monitoring the oil through the year I always noted decent colour and no 'mayonnaise'.

Following Paul's suggestion I went onto several websites and discussion forums from both sides of the Atlantic to look up Ametech Restore and, as you say, opinion varies from "It's brilliant" to "It's snake oil" and I confess it did look a bit too easy to me. However, as it would only be short term and one could question the degree of damage it could do to an already condemned engine I think I'll try it, get any outstanding fault codes cleared and see if it can boost compression sufficiently to make the MAP sensor behave (I forgot to explain earlier that the service agent says the sensor's use of vacuum means compression is an issue in its operation).

In the light of what you've said, future everyday use of the car on the IOM will need close attention to more frequent oil changes and use of other cleansing products if the car is to survive into a respectable old age.

[J44EAG]

If you do consider a rebuild at some point in the future, Neil, this link will be useful to you.

It is a superb Jaguar PDF document on the modular construction of the V8 (also V6) motor. However, despite this document, rebuilding a V8 will be a long and I would think painful process due to the way that the crank and rods have been electronically sized at build stage for bearings. These would be difficult if not impossible to source from Main Dealers. They would want to sell you a new engine!

Racing Green Cars though, do offer a solution and this is where I would start if I were to attempt a rebuild. Far easier and probably cheaper though to source a good second hand block with warranty for around £600! Rebuild costs really do build up very quickly both for parts, labour and machine shop time. The old block though would make a great parts donor source. ie heads,valves, camshafts, VVT, water pump, idler pulleys etc.
http://www.google.co.uk/url?sa=t&rct=j& ... NwdrKUf4YQ

These two links cover more general aspects of the engine. Select XJ to download or view the correct publication for your car.

http://www.docs-library.com/pdf/1/1/200 ... chure.html#
http://www.jagdocs.com/index.php?main_p ... ath=69_116

One aspect of rebuilding an engine to consider is the amount of physical exertion required just to handle an engine sat on a pallet. That should not be under estimated. Despite being aluminium, a V8 is still quite a challenge to handle as I recall it weighs around 440kg when fully dressed. A decent crane and engine building stand would be needed to avoid personal injury through body strain. Such units tend to stick themselves to the floor and become immovable if working single handed. Regret PTJS1 and myself would be unable to assist. We both have clapped out backs!

I think the issue you have is almost certainly down to short journey use, slightly but perhaps not solely down to living on a small island. The situation is perhaps similar to cars used on the Channel Islands or the Isle of Wight. As we know there are plenty of large engined cars in those locations being run successfully. Similarly, there are Mainland cars that only do short journeys and which could also be classed as potential victims of the dreaded bore wear syndrome. My own S-type could easily fall into that category although I do have the advantage of being able to have a good blast down the M27/A27 corridor along the bottom of the South Coast from time to time.

Your might consider adding a can of flushing oil additive immediately prior to an oil change before adding Ametech. This would give you two bites at attempting to regain cylinder pressures. Flushing additive should only be used at idle speed for twenty minutes or so in an attempt to soften and break down carbon deposits within the engine. Around 500ml of the fluid is added to engine oil, the engine run and then oil and filter changed. The additive will reduce the viscosity of the oil to that of water! What is removed will be deadly black with carbon contamination held in suspension. Vacuum extraction or sump plug removal then allows an oil and filter change. At that point you could add some Ametech and hope for some improvement.

An interesting topic. Just sorry to hear you have the issue.

Mike K

[ManxNeil]

Again, thanks for all the trouble you've gone to in sharing your knowledge and imparting the advice, Mike.

I've had the engine out of my Mk2 and helped others with all sorts of engines, and am sure the AJ-V8 is no pushover! I have an engine crane and a building stand but these are for moving and working on the engines of my classics, the stand was purchased specifically for the rebuild of a 4.2 XK unit from a Series 2 XJ6 which is intended for my C-type rep. kit. I'm sorry I wasn't more clear in why I would like to have the 350's existing engine in my workshop - it would simply be to examine it, as I'm curious as to where and exactly what the failure actually is. I wouldn't be prepared to undertake the rebuild of a comparatively modern engine; the second paragraph of your last message says it all.

I'm going to follow combined advice given by yourself, Paul and Rob. Eurojags has one suitable engine in at the moment, a running 82,000-miler from a 2004 car for only £500+VAT and delivery. I'm having it sent down to XJK, hopefully by this Friday, and taking the car over next week for the two days' (all being well) transplant work. XJK will then ship the old engine over to the Island. It's a risk, I suppose, but one I've decided is worth taking. I will have the car back on the IOM in time for its existing appointment at the local Jag agent for an investigation into the failure of the front dampers - see elsewhere on this forum! If all goes well, I'll have bought an extra 25,000 miles for the car engine-wise, at least. (By then, the XF may even have grown on me sufficiently to commit as an everyday car...)

Hovering over this is finding out yesterday that a local (non-aligned) dealer has two V6 petrol Sovereigns in, one local '05 and the other a year younger. Both have 67K miles but the latter is fresh over to the IOM, still on UK plates. I could certainly beat him down on the £9,995 asking price for each, if I were inclined. My preference for any replacement X350, however, would be a diesel or another V8, but what is the view of the knowledgable about the petrol six-banger?

Cheers,

[davidr]

Neil - I wouldn't be looking to buy a diesel in your situation. They work best with regular long runs and your short trips on the IOM would clog up the diesel particulate filter in a very short time. It needs a steady run of about 20 minutes or more to regenerate so I would steer clear.
As you'll see from my car history, I'm not biased against the diesel - I used to own one and it was just about the best car I've ever had!

[ManxNeil]

Point taken, David, but most of the XFs over here - and there are quite a few - seem to be diesels. A friend has an XF-S and I've been hugely impressed by its performance and economy. I'll stick to a gas guzzler, then, at least while there's still gas to guzzle.

[davidr]

Neil - I used to have an XF diesel S (3.0ltr V6 uprated to 275bhp) and it was a properly quick car. It did 0-60mph in less than 6 seconds And I used to average over 40mpg! But my journeys were almost always over an hour so it did the miles to both keep the DPF clear and take advantage of the economy. If you don't do many miles then the diesels are a false economy in my opinion.
The V6 petrol is still a good option. Performance in the x350 is adequate as the body is so light and there isn't much that goes wrong with that engine. Economy isn't too bad either, again because of the light body.

[J44EAG]

Our Mr Marks voiced an opinion about the economics of running a 2.7 diesel at the last S-type seminar. He considered that due to the high servicing costs of running a diesel, unless you are covering at least 30k miles per year, a petrol V6 would make the cheaper option.

Many of us can self service V6 and V8 petrol models without difficulty. The diesel however is a rather different matter in view of the amount of special tools and test gear needed to keep a diesel in tip top condition. Regeneration requirements and DPF issues make the diesel potentially problematical for repeated short journey use.

The V6 petrol unit especially in the later constant variable VVT form linked to the ZF gearbox makes for a good combination in a 350. Given the light weight of the car, the V6 is more than adequate for most driving conditions. However they do need regular oil changes at recommended service intervals. If that has not occurred then there is an increased likelihood of top end oil starvation due to oil breakdown and carbonisation. I understand there are small filters in the VVT units which must be kept clear of sludge and debris to ensure a good long service life. Rob J currently has a 350 with 270k miles on he clock which is still running and driving perfectly.

Mike K