Changing the exhaust manifold gasket
Discussion
My drivers side, rear exhaust manifold gasket is blowing. I've bought the gaskets, and am going to try changing it this weekend.
However, looking back at the cars service records, this was only done in August 2004! The heads had to be removed to drill out and re-tap the threads for the bolts as they had been - to quote- 'rounded off'. The replacement bolts are 'cap head' type - the ones that take an allen key (8mm size I think) there are also some normal head ones on there - these must be on the holes that haven’t been re-tapped. The question is, would these make it more difficult to remove the manifold, as access - especially to the most rear lower bolt (allen type) seems very tight, and to get an allen key in there (or even a socket with an allan adaptor on it) looks impossible due to the location of the chassis rail. Hopefully though if the gaskets were only changes a year of so ago, then the bolts shouldn't be too tight (fingers crossed touching wood etc..)
Should I use any kind of gasket sealant? I have seen mentioned the use of anti-seize compound as a gasket sealant for exhaust manifolds - I will be using this on the bolts when I put them back in!
Also what is the length of these bolts if I want to get some replacements (although I'm still not sure if the allen bolts are now a metric size as the holes have been re-tapped.)
Cheers,
Toby.
>> Edited by Tobs on Wednesday 30th November 10:22
However, looking back at the cars service records, this was only done in August 2004! The heads had to be removed to drill out and re-tap the threads for the bolts as they had been - to quote- 'rounded off'. The replacement bolts are 'cap head' type - the ones that take an allen key (8mm size I think) there are also some normal head ones on there - these must be on the holes that haven’t been re-tapped. The question is, would these make it more difficult to remove the manifold, as access - especially to the most rear lower bolt (allen type) seems very tight, and to get an allen key in there (or even a socket with an allan adaptor on it) looks impossible due to the location of the chassis rail. Hopefully though if the gaskets were only changes a year of so ago, then the bolts shouldn't be too tight (fingers crossed touching wood etc..)
Should I use any kind of gasket sealant? I have seen mentioned the use of anti-seize compound as a gasket sealant for exhaust manifolds - I will be using this on the bolts when I put them back in!
Also what is the length of these bolts if I want to get some replacements (although I'm still not sure if the allen bolts are now a metric size as the holes have been re-tapped.)
Cheers,
Toby.
>> Edited by Tobs on Wednesday 30th November 10:22
look at my site www.snorky.co.uk for write up but I didn't have allen bolts which as you say will make it harder. Not a difficult job but a pain in the ass to do...
Make sure that you have a selection of good quality spanners. Take very great care so that they do not slip and round off the bolts. Some bolts can only be moved a fraction of a turn before you have to change spanner or approach from a different angle. I'd also fit new bolts as a matter of course.
I believe that the factory fitted the manifolds with the engine out!
Do-able but a real pain. Expect it to take all weekend. The good news is that you're doing the easy side.
I believe that the factory fitted the manifolds with the engine out!
Do-able but a real pain. Expect it to take all weekend. The good news is that you're doing the easy side.
That's the easy side? Oh bollox. I did that side last weekend and it took me 3 hours; I ended up removing the engine mount on that side and jacking the engine up to get clearance. The top ones were a lot easier with the heater pipes removed.
I have the passenger side to do tomorrow, and I was hoping it would be easier.
I did have a set of stainless allen bolts to fit, but looking at them I can't see how you'd get an allen key onto some of them. I gave the set to the guy next door for his Rangie - clearance is somewhat less of an issue for him!
Are studs an option?
Edited to add: good writeup Snorky, very useful. One thing you missed, which helped me: Using the right 9/16AF spanner is of course essential to get the bolts loose (and I wouldn't use a ring spanner for this, you do not want to round those b*ggers); but once you've loosened the bolts, a 14mm metric will do just as well while prividing a tiny bit of slack to make the job easier. This is of course if you don't have a ring spanner (or if, like mine, your ring spanner is too "well built" to fit twixt bolt and pipework).
>> Edited by victormeldrew on Wednesday 30th November 16:03
I have the passenger side to do tomorrow, and I was hoping it would be easier.
I did have a set of stainless allen bolts to fit, but looking at them I can't see how you'd get an allen key onto some of them. I gave the set to the guy next door for his Rangie - clearance is somewhat less of an issue for him!
Are studs an option?
Edited to add: good writeup Snorky, very useful. One thing you missed, which helped me: Using the right 9/16AF spanner is of course essential to get the bolts loose (and I wouldn't use a ring spanner for this, you do not want to round those b*ggers); but once you've loosened the bolts, a 14mm metric will do just as well while prividing a tiny bit of slack to make the job easier. This is of course if you don't have a ring spanner (or if, like mine, your ring spanner is too "well built" to fit twixt bolt and pipework).
>> Edited by victormeldrew on Wednesday 30th November 16:03
Hughesie2 said:
Dont Bother, seriously get someone thats used to doing them to do it for you, it took me most of the weekend to get the easy ones off, local indie would do it in a couple of hours max !!
I'm with Hughsie on this one. Austec did mine, one of the bolts had been cross-threaded and was unremovable. Ended up having to take the head off, send it away (couldn't be drilled/retapped) to be spanked with a huge spark-type-effort. Wouldn't have wanted to deal with that on my own!They are much easier to fit, but I'm not too sure about the stainless/ally combination if you are fitting them straight into the heads. I expect they'll be OK on mine because I've got steel inserts, but if they're fitted straight into ally I think there may be an electropotential corrosion problem.
Tobs, most of the other tips have been covered but I used fuse wire to hold the gaskets in place (through the bolts holes in case you wondered). The bolts can be started and then the fuse wire cut and Robert’s your uncle. Good luck, oh and get some cream for your hands you will need it!!
GreenV8S said:
They are much easier to fit, but I'm not too sure about the stainless/ally combination if you are fitting them straight into the heads. I expect they'll be OK on mine because I've got steel inserts, but if they're fitted straight into ally I think there may be an electropotential corrosion problem.
That is correct. When I was working on all ali components the worst combination for potential cathodic corrosion is an ali/stainless contact. Where this could not be avoided we had to anodise the ali bits. Not really an option on threaded holes!
Did you also order the extra part that curls round the manifolds nuts to stop them vibrating loose?
(sorry cannot think of its name). I was suggested these when I ordered the exhaust gasket kits from a main land rover company!! and only an extra few quid.
Just an extra addition to stop that ticking noise coming back.
>> Edited by scared but happy on Friday 2nd December 10:35
(sorry cannot think of its name). I was suggested these when I ordered the exhaust gasket kits from a main land rover company!! and only an extra few quid.
Just an extra addition to stop that ticking noise coming back.
>> Edited by scared but happy on Friday 2nd December 10:35
Well I was going to change the gasket today, but when I started removing the manifold bolts I discovered the majority of them were only finger tight! So I abandoned the idea of changing the gasket and just (well I say just! - still took an hour or so) tightened all the bolts up - all seems OK now I think! I'll have to wait and see if that has solved the problem.
I also tightened up the passenger side manifold as some of these bolts were also quite loose.
Toby.
I also tightened up the passenger side manifold as some of these bolts were also quite loose.
Toby.
Tobs said:
Well I was going to change the gasket today, but when I started removing the manifold bolts I discovered the majority of them were only finger tight! So I abandoned the idea of changing the gasket and just (well I say just! - still took an hour or so) tightened all the bolts up - all seems OK now I think! I'll have to wait and see if that has solved the problem.
I also tightened up the passenger side manifold as some of these bolts were also quite loose.
Toby.
Hi Tobs,
I have hte same problem with my bolts too. Have to tighten them up every month or so. Since the car is in for a service I have asked them to fit spring washers to the existing bolts and/or replace any where necessary. They are a pain to get to to have to do this all the time yourself.
Good luck
Corey
Hi Toby, I had the same problem, whatever I tried I could not get a spanner on the bottow bolt of the rear most manifold bolt. In all my years of motoring I have never resorted to a dealer, prefering to do all maintenance work myself. But gave up with this in disgust. Got Topcats of Aylesbury to do it for me. Their labour rates are very good and they do an excellent job. I highly recommend them, great company. People come from miles around to get their TVR's serviced by them. There is always a stack of TVR's in their car park. They have a webb site.
good luck, jack
good luck, jack
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