For all things Rover V8, the TVR Griffith and Chimaera and TVR T-Cars
There is little doubt that exhaust gasket replacement is one of the more fiddly tasks on Griffs and Chims and it is one which can test the patience. However, Roger Penny had a go and was successful. He gives a no holds barred account of his experiences and, most remarkably, a special tool that he invented himself.
He will describe working on the offside head only. The procedure is virtually the same for the nearside except that the exhaust needed to be dropped. See HERE for dropping the exhaust.
Roger describes the noise as a ticking or farting linked to revs, louder under load and almost disappearing on lift off. There was no noticeable fall-off in performance. These are not definitive of course and further investigation was required.
He was unable to pinpoint the source just by sticking his head under the bonnet so used a piece of garden hose and placed one end on various parts of the engine that he felt might have been guilty. By sticking the other end near his ear he was able to magnify the local sound. The noise proved loudest by cylinder number two exhaust outlet. Whilst it appeared only one gasket was leaking, he thought it best to change them all.
Each exhaust manifold is held by eight 14mm bolts to the head. To access some of the lower bolts it was necessary to go under the car so it needed to be jacked up and the front wheel removed. Roger draped an old towel over the wing for protection. He also disconnected the battery. Whilst this last bit might not seem absolutely necessary, it becomes clearer later. The picture shows the car being jacked up. Most authorities suggest that you should not go under a car unless it is securely supported at least on axle stands, and many feel that there should be additional safeguards as well. See SAFETY.
He made a note of the order of the plug leads and pulled them off, tucking them away without bending them as they are easily damaged. He removed the spark plug shrouds, but left the plugs in place.
He was surprised to find that undoing some of the bolts proved easy. Indeed three were only finger tight – see NOTES below. But even so, Roger found it a bit of a fiddle as he was able to turn some of them only a flat at a time. A selection of 14mm spanners, open, ring, ratchet might well be felt worth the investment. But no matter how many you have they are a fiddle – difficult to get at and some you can only turn half of a flat at a time.
The gaskets are twinned so there is one to each pair of ports. They have an up and down. The bar ‘connecting’ the two parts goes at the bottom.
As a general rule, the upper bolts are accessed from above, the lower ones from underneath. The starter motor terminals are very close to the lower bolts for the two rearmost offside lower bolts, as mentioned before, Roger had disconnected the battery for safety reasons.
Some people disconnect the live feed for the starter (red arrow in the picture, right) to give slightly more room and some even feel it worthwhile to remove the starter motor altogether for lots more room. See NOTES at the end of the article. Roger described removing the rearmost lower (yellow arrow in the picture, right) as a right fiddle.
He found that the lower middle two bolts were difficult, if not impossible, ro withdraw completely until the manifold is moved back from the cylinder head slightly because the pipes for these two cylinders are so close to the bolt head (they are lower down) there isn’t room for the length of the bolt. He made a mental note for the reassembly procedure to the effect that these would have to be put in whilst there was still some movement in the manifold.
As Roger’s Griffith is a ’98 500 Griffith, he had to disconnect the Y-piece to move the manifold – it was solid. He undid the bolt and taking a great deal of care, tapped the steel band to break the seal. The sealant round the Y-piece needed to be scraped away. He used an old screwdriver and wire brush. Other models with different exhaust layouts may need a different approach. Roger said that replacing just one gasket was not quite as easy as some have suggested and, given how cheap they are and that the main difficulty is removing the manifold bolts, it makes sense to replace a whole side each time.
When Roger removed the gasket he ‘rebuilt’ them to ensure that he had got all the bits. I’ve got so say that this is an eminently sensible idea. Even so, he used his finger to check that the faces of both the head and the manifold were clear of any lumps or unevenness.
He ensured the threads were clean by dabbing a bit of copper grease on each bolt and screwing it back into the head whilst the manifold was off. This made it easier to get replace the bolts.
Replacement of the manifold, according to Roger, is a simple, but still fiddly, reversal of the process.
He used Gun Gum as the sealant for the Y-piece, although any proprietary make would do. He fitted the two bits together first without doing the steel band up fully and the play that this left with the manifold was essential for ease of replacement.
He dabbed some suitable exhaust manifold sealant round the new gasket. This has to be proper exhaust gasket sealant as it takes very high temperatures. He put them to one side ready for use.
Then it was time for the bit that Roger described as ‘the hard part’.
He positioned the gaskets one at a time checking they are the right way round, firstly on the front two and then the rear two. He slid the upper bolts in through the manifold and then slid the new gasket over the bolt. He found the new gaskets could be slid into place from between cylinders the two pairs of exhaust outlets. There is space.
When replacing the front gasket, he slid it in and slotted it over the rear upper bolt then pushed the gasket round to slide it over the uper front bolt. For the rear gasket, he slid it over front upper bolt then over the rear upper bolt. He then screwed the bolts into the head for a couple of turns using his fingers although he did not tighten them. This ensures that the gasket and manifold are positioned properly, and that the bolt is not cross threaded.
Then it was time for the bit that Roger described as ‘the fun part’.
Although the lower front bolt can be accessed from the top by those without fat fingers, Roger did replaced all four from underneath. Again he turned the bolts a couple of times with his fingers to ensure they were not cross threaded, and that they won’t fall out.
Roger found replacing rearmost lower bolt back in a challenge. However, in the great tradition of British eccentricity he made his own special tool. He explains:
“Here I present to you my (patent pending) bit of stick with string. I took a 5mm square, 20 cm long piece of wood (these measurements do not have to be exact). I gaffer taped a piece of string towards the top, and then placed the bolt on the top of the stick, and held it down with the string. From underneath the car, you can slot the end of the bolt into its hole, let go of the string, and give it another shove with the stick. It took me about two hours of toil to work this out. Then it took less than a minute.
Illustrations from left to right: the basic tool - the bolt attached - detail of bolt. Given times quoted for locating the final bolt, Roger’s special tool seems a superb and simple solution to a difficult problem.
It was then time to tighten up all of the bolts. Firstly, he used fingers to screw in the middle two bolts as these would foul the exhaust pipes otherwise. He did the rest up finger tight as best he could. Land Rover shows a torque of 15 ft.lb. for exhaust manifold bolts, so he used this, but was unable to get a torque wrench anywhere near most of the bolts. As can be seen by the picture, right, it is difficult enough getting an open ended spanner on some.
He torqued up the upper front bolt a torque wrench, but held the wrench about the length of the spanner he would be using for the rest of the bolts. This gave him some ‘feel’ for how tight he needed to go. As he says, he was putting steel bolts into an alloy head and stripping the thread is a real bad idea.
He used an open spanner for the rest. For numbers the middle two lower bolts the spanner fouls the exhaust pipe, and he found it too easy to think he had tightened up the bolt when in fact he was just pushing against the pipe itself.
See NOTES below re spanners.
It was just the steel band round the Y-piece that needed bolting up after that.
He refitted the shrouds and plug leads, re-connected the battery, re-fitted the wheel, and dropped the car off the axle stands.
He fired up the engine but didn’t rev it. He let it idle for a few minutes to get some temperature into the gasket sealant and to make sure there are no leaks.
After running the car for a few hundred miles he checked the exhaust bolts to ensure they were still tight.
It should be remembered that checking the exhaust manifold bolts is a regular procedure in the service schedule. See HERE. It is possible for the bolts to shake loose with vibration and many people feel that they should be checked for tightness, if not for torque, at each service.
If you find that, using the method above, you have a leaking exhaust gasket, it might be worthwhile to tighten the bolts and then see if the problem persists.
A leaking exhaust gasket can damage the metal around the exhaust outlet, or even the manifold, so it might be a risk too far if the sound is only made quieter and not eliminated altogether. By continuing to run the engine you might cause damage that, had you replaced the gasket, would not have occurred.
It is unfortunate that the sound is not distinctive but any ticking should be investigated. A leaking exhaust gasket is one of the problems that is best solved early.
Different spanners, ‘bendy’ ones.
Of course the spanners do not bend. What it means is that the jaws are offset. These can be extremely useful in tight situations, such as the exhaust manifold bolts. Whilst they seem expensive they are invaluable when needed. Another option is machining a spanner that is, for instance, too long or the jaws are just that bit too wide. You should keep it just for that one nut.
A garage mechanic suggested that it can be ‘useful’ to remove the bolts from the starter motor on RV8-engined cars every other year as they have a tendency to seize and can be difficult (not his word) to get out one they’ve been left for some time. He said he coats them in copper-slip every time but even then they often need a bit of effort. It is essential, he said, to replace any damaged bolts and not to replace them. This is the universal mantra of any decent mechanic.