| Author | Message | ||
     Omar M. Shams Prolific User Username: omar Post Number: 161 Registered: 4-2009 |
Oh woe is me!! I am confident I have blown at least one head gasket. I should have read the signs over the last 4 months.......... Never mind!! The damage is done, and now I have to face up to the necessary repairs. I am led to believe that just changing the head gaskets will not necessarily work. I have been told that many a person has changed head gaskets only to find that the liner seals had also failed at the same time as the gasket rendering the gasket replacement a waste of time. Is there anything I can do to ensure that once I have replaced the head gaskets I will have a good strong engine again? Naturally, I will skim both heads and decoke them too. Are there any liner seal repairs that can be done when the heads are off to prevent me from having to tear the whole engine apart and thus do an engine overhaul? | ||
| David Gore Moderator Username: david_gore Post Number: 978 Registered: 4-2003 |
Omar, Bill Coburn has done a series of articles on overhauling a Shadow V8 in Tee One Topics and these might be a useful starting point for you especialy the sections on removing the heads and the cylinder liners. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 652 Registered: 6-2006 |
Omar  "I should have read the signs over the last 4 months" What signs. Head gaskets do fail and can be changed without the liner seals. If the engine has been badly cooked - then the liner seals may be suspect. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2206 Registered: 4-2003 |
Omar, A bit of encouragement: if the gaskets have shown a progressive deterioration, then the failure is most likely not catastrophic. A head gasket which blows completely and without warning is the nasty one. The main thing to do is to find the cause, usually a dodgy or substitute thermostat being the culprit. These motors are not known to blow head gaskets without a major reason. However, overheating can f course destroy the motors quick smart. I don’t know for sure, but it may just be that some of the latest coolants are not good for the gaskets (refer to the Boddice factor on using the correct coolant for the liner seals). True, the liners don't like to be disturbed by removing the heads. Once a head has been removed the liners are more likely to be troublesome, but again these motors are well ahead of the pack in liner reliability. Usually, they lose oil through the weep holes long, long before any coolant or cylinder pressure issues arise. Indeed, most of these motors with oil seepage through the weep holes have had their heads removed at some stage. If the liners don’t leak coolant, then there is probably nothing to worry about. On skimming, do try either not to have the heads skimmed if they are perfectly flat, or at worst remove the tiniest amount possible. That takes quite some extra time to set up, but it is worth it. These heads are good for two <normal> skims before they are scrap. Take heart. The heads of our T-Series have been off twice: once at 98,000 miles and again at 98,500 miles. Er. The Australian distributors removed the heads for a Valve Grind (remember what a Valve Grind was ?) when in fact there was a minor fuel blockage in one carburettor. Yep, they ground away the stellite valve faces, so new valves were needed a few weeks later. It has now done well over 200,000 miles trouble free. Worst case is to change a liner in-situ. With the heads of and the sump removed it is not really difficult. You need a conventional liner puller borrowed from a diesel truck shop and a bucket full of dry ice. The dry ice chills the liner prior to extraction and again prior to popping it back in. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 162 Registered: 4-2009 |
Dear All, Many thanks for the words of encouragement. I will give it a go when I have some time. The car may go on hold for a few weeks till I get the time, but i will certainly give it a go. The signs were: Top hose bursting. poor idling overflow tank bursting second overflow (supplied new a month ago) bursting losing coolant engine running at higher than normal temperature | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2207 Registered: 4-2003 |
Good luck, Omar. To state the bleeding obvious, I assume that the thermostat is genuine and not stuck or missing, as any of those would cause exactly such symptoms. RT.. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 653 Registered: 6-2006 |
More importantly - the radiator cap must be faulty or wrong as both top hose and header tank should stand more than the 13 PSI that these should 'break' at. Unless the gas getting into the system is entering so fast that it does not have time to escape through the cap. (unusual) | ||
| Omar M. Shams Prolific User Username: omar Post Number: 163 Registered: 4-2009 |
As it happens, my test to conclude head failure was this: I removed the old thermostat (which I did not test upon removal) and removed the guts out of it to take away the restriction to see if pressure still builds up in the cooling system. Yes it did. So for me, that was the nail in the coffin. The cap I had was a 110 Kpa or 15 psi one. For someone who has never removed a head from a Roller, how will I know if the liner seals are good once the heads are off? | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 821 Registered: 9-2004 |
Hi Omar,worth doing a cylinder leakage test first on each cylinder in turn. This will confirm the if both head gaskets or only one have failed, also it will point to the cylinders if failed for closer examination if the liner has sunk etc etc. Do not do a tear down at this point of time. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 164 Registered: 4-2009 |
Fantastic advise Patrick. What is the best way to do cylinder leakage test? Thanks Omar | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 654 Registered: 6-2006 |
Hi Omar, A couple of observations. Gutting the thermostat is not a good test because the bottom plate lowers as the water gets hotter and blocks the bypass pipe. Although I do mention this, with the thermostat out, it will usually over cool in any case. (water prefers to go through the radiator. Cylinder leakage test - often not conclusive for head gasket faults. 150 psi against 2000psi??? of a cylinder firing. Much better at valve and ring faults. Is your radiator working properly? I had a Turbo come in for head gaskets recently - blowing water out of the cap, too hot, etc. Turned out that 90% of the radiator channels were blocked. Use an IR temp gauge or your hand to feel across the fins of the rad. All should be hot & at around the same temperature. To test for headgasket leaks use a BLOCK TESTER. this is a chemical that checks for CO2 in the engine coolant by changing colour. The tool plugs into the radiator cap ( or on the bleed screw hole on plastic tank rads like yours) Tricky but possible. Just googled it for a pic and this one came up which looks like a copy of the snap-on one I have, with two chambers. A bargain at £35. Combustion Leak Detector (Message edited by david_gore on 18 September 2010) | ||
| Omar M. Shams Prolific User Username: omar Post Number: 165 Registered: 4-2009 |
Many thanks for your input Paul. I took the radiator out for a service as I must have been leading up to the failure. This was one of the indicators that I forgot to mention. The rad is not like new, but good to use. The thermostat in the car now is nothing but a small restriction. with the engine running and the radiator cap off, i can see water coming out with lots of bubbles in between gushes. also, the water comes out very hot whilst the car is at idle from cold. I definitely have a blown head gasket and maybe even worse. I very much like the idea of establishing which head gasket has gone.to fix one rather than 2 is music to my ears. the question is, how will I know which one has failed and after that has been sorted, what to look for regarding liner seals. If a head gasket will blow anywhere in the world it would have to be the Arabian Gulf. The summers are very harsh indeed. having said that, I have run Rolls-Royces for over 15 years here and never had head gasket problems. I put it down to the previous owner running the car without a thermostat. Thanks Omar | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2209 Registered: 4-2003 |
Omar, All Paul’s points are good advice. Sure, if the gasket is badly blown, then a leakdown test just may give an indication. Better still, air leakage to the coolant will give a positive diagnosis. My compressor will give out 150psi, so maybe that would do. If air bubbles out the header tank while a cylinder is pressurised, then you will know where you-re at. I have lots of tricks to find which head is bad and so-on, but I do reserve them for Holdens and Fords as you must run the motor. In other words, I strongly recommend that you take extreme care, and preferably do not start the motor again until the problem is found and cured. However, it IS safe to run the motor PROVIDED first you disconnect the ignition coil[s, turn the motor over four revolutions or so to check that there is no coolant in a cylinder. Then reconnect and run the motor. If, while crankin the motor without ignition, the motor stalls the starter, then you need to find which cylinder is full of coolant. The good thing is that then you have found your problem. Read on. Warning: if the head gasket IS blown, then it is very dangerous to start a Crewe V8. I know of a few bent conrods on Silver Shadows caused by blown head gaskets, One I saw was on a Silver Shadow at York Motors, Sydney, in 1984. The gasket had blown, and the owner tried to start the motor the next day. Overnight, coolant had partially filled one cylinder right at the start of its compression cycle. When the motor cranked and another cylinder fired, BANG. The incompressible coolant won over the conrod, and the rod bent like a banana. Yorks fitted a new piston and liner in-situ. I enjoyed the invitation to watch the liner and piston being installed. Lastly, Paul says that an engine runs cool without a thermostat. That-s usually true of these motors, but when pressed they can overheat badly too. I did a flow test once on my R-Type which also has a bypass thermostat. Without a thermostat, the flow through the radiator dropped to 35% with the bypass hose open compared to 100% when blocked off with a clamp. That means that the engine will run uncontrolled temperatures, too cold mostly which is shocking for wear, and too hot sometimes. Of course, the motor runs best and safest as hot as possible so long as the coolant doesn’t vaporise. Once the coolant boils, the gaskets blow and worse. The V8s may have less radiator flow or more, but whatever the case a proper thermostat, one which blocks the bypass when hot, is essential. RT. (Message edited by Richard Treacy on 18 September 2010) | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 656 Registered: 6-2006 |
Omar, Sorry, I meant to mention that the only way of telling what the liner seals are up to is by looking at the tell tales on the side of the block. The liners can't drop because they are metal to metal, the seals are between the wall of the liner and the block. They protrude slightly and the head holds them down. If you are getting that much gas, take plugs leads off or plugs out (if you sill get lots of gas ) one at a time and then run the engine. If you do not get any gas in the water, then that is the cylinder with the problem. (there may be more than one leaking so you may end up doing two at a time etc. ) I'd recommend both heads are done as the gaskets have had the same use. I've never come across an aluminium head that hasn't needed some amount of skimming once removed. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 166 Registered: 4-2009 |
ok guys. the advice appears to be "do both heads". I am all for advice. Should I do both heads anyway and hope the liner seals are ok at the end of the repair? | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 822 Registered: 9-2004 |
Omar, Many problems can arrive through excess heat with liner sinkage, distortion due to the different make up of iron liners and the alloy block! The correct protrusion will not cure a tipped liner seat. Many engines have failed after replaced gasket etc. Have posted procedure for cylinder leakage test years ago. But a quick refresher. First remove all plugs. Use the whistle to find TDC on the first and every cylinder to be tested turning the engine by hand NOT useing the starter. Lock the flywheel on each cylinder TDC. Use the leakage tester on the cylinder, you will be able to check every cylinder for piston blow by, cracked head, valve blow and of course head gasket failure. Hope this helps,now back to the party RKH brings home the loot! | ||
| Omar M. Shams Prolific User Username: omar Post Number: 167 Registered: 4-2009 |
Dear Patrick, Thanks for the advice. 1- How do I lock the flywheel? 2- whistle?? I may need some help to translate this one into Arabic. 3- Party .... RKH... Loot..... this line was wasted on me.........I think your Arabic must be even better than mine!! | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 823 Registered: 9-2004 |
1- How do I lock the flywheel? With a flywheel gear lock. 2- whistle?? I may need some help to translate this one into Arabic. Whistle connects to the hose plug adapter, on the compression stroke as the crank turns the whistle sounds up to TDC.Flywheel is locked in this position. The cylinder leakage tester is connected instead of the whistle to the hose plug adapter. 3- Party .... RKH... Loot..... this line was wasted on me.........I think your Arabic must be even better than mine!! OK of topic but the excitment got the better of me. Rockhopper is a Falkland penguin however it is the symbol RKH for Rockhopper Oil Exploration in the falkland that has hit oil. The price keeps going skywards Just happens that i hold thousands @ penny share prices. If I sell though CGT is 50% but still enough for a new Bentley or RR. Tip! Desire DES worth a punt. DYOR though. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 170 Registered: 4-2009 |
Dear Patrick, good luck on the RKH.............. I don't have sohpisticated flywheel locking whistling tools in my toolbox, so I will go without on this occasion. Dear Team, I have removed the spark plugs to see if there were any stories that they could tell. The diagnosis is that the cylinders are all firing evenly with no signs of deposits of any kind. All perfectly normal. Two shameful observations however: The garage that I had been using (which I have since struck off) had ensured that I had 2 fingertight plugs and a mish mash of two types of spark plugs. I was horrified!! After what I had corrected from their previous blunders on my green Wraith II, I was purposely looking out for poor workmanship, and yes we have two examples of that just by removing the plugs. I will now buy replacement plugs prior to doing a compression check. What should be the right type of spark plugs for a 1990 Turbo RL of Japanese spec?? | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2226 Registered: 4-2003 |
For all postwar cars, MkVI, SC, SY SZ alike, NGK is the only one. Addressing the V8s only: S2, SY and SZ, Turbos and all: GR4IX Iridium, the best. By far. Good for 400,000km. BPR4EVX Platinium. Old stock, but the best until about 8 years ago. I put a set in a 1990 Turbo R a few hours ago. Shame. Pretty ordinary but perfectly good, as they only last 180,000km. BPR5ES etc. Conventional plugs. Not bad. Ideal for cheapskates. Still very good for just 50,000km. Better BPR4ES. RT. RT. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 667 Registered: 6-2006 |
or BKR4EVX Although Richard has the numbers right he has the descriptions wrong. . . . the best. By far. = incredible (I'll let you off with that though.) Pretty ordinary but perfectly good = Amazing Not bad = Excellent You will be offered alternatives which will range from diabolical to pretty good . . . but even the best will not match the basic NGK BPR5(4)ES. Unless you are likely to do 50,000 a year, you should still whip them out every two years in any case, even if it is just to check them. Otherwise you will end up with stuck plug caps and threads. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2228 Registered: 4-2003 |
.... and hit the threads with Nickel Antiseize every time. By far. I used mere Silver Antiseize this afternoon. Not bad. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 171 Registered: 4-2009 |
many thanks for that guys. gap of 0.6mm ok???? | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2229 Registered: 4-2003 |
NO WAY. They need 1.0mm. Yes, 1.0mm, 0.040". That is the most important thing about the plugs in your car. Its is a wide gap very intentionally. They come gapped correctly out of the box (the NGK number defines the gap by the way). RT. | ||
| Omar M. Shams Prolific User Username: omar Post Number: 172 Registered: 4-2009 |
wow!! many thanks Richard. |
