Exhaust manifold threads stripped............ideas please

[gmsclassics]

This is the 79 pageant blue Sprint I bought in early '99 and has done 30,000 trouble free miles since. I had to sort out the steering and suspension when I got it but have done nothing mechanical, other than a new clutch. Neither head or sump have ever been off. Anyway, the exhaust started to go so I thought as this is the car I will always keep, investing in a stainless unit would be the way to go. Old exhaust came off without issue but when tying to bolt up the new stainless twin downpipe the middle/inner bolt (new) started to just go round and round in the manifold. I can't see but it felt like an old (rusty) helicoil has given up and started to pull out.

I can't see any way of putting in a new helicoil in situ, there just isn't the room. I've got a kit the right size. Next I thought of removing the manifold, another job that isn't easy in situ as you can't get a socket on all but the front bolt - and you guessed it, I can't turn any with a spanner. Bolts look very rusty as you would expect so I've left them soaking in WD40 but whether that will work is debatable as it will be a long time since they were undone, if ever.

The next option can only be taking the head off, but heaven knows what trouble that could bring............

Any ideas or tricks I could use anyone? I don't want to dig this hole deeper than I have to.

Geoff

[cliftyhanger]

Many years ago I had a similar issue (sprint engine in my spitfire)
My solution was to retap the holes 12mm (from memory) and I think I drilled the downpipe holes to suit. All a bit hazy as 23 years ago now...
Allen headed bolts would be slim to fit.

[Jon Tilson]

Sorry Geoff but you have to swing it all out to sort this.

You cant do anything meaningful to a Sprint exhaust manifold so as you say you could take off the head but its a shame to disturb the head gasket and inlet manifold
when nothing is wrong.

Its worth it for all the other stuff you can do when its all out....engine and box out together would be my advice.

Jonners

[mahony]

You do not have to take off your cylinder head to remove the exhaust manifold on a sprint, I have done it several times in situ ( not with spanners but with a socket set ), read this. viewtopic.php?f=4&t=27042&hilit=+manifold

[gmsclassics]

Thanks Jon, I was thinking that was the case but needed to hear you say it. I think it will get pushed into the corner of the barn as that'll take a bit longer than the day I had put aside for the exhaust!

I'll have to start thinking of the what else while its out. It's been leaking oil from the three O-rings on the gear selector rods so that is one. Clutch was done 6 years ago so that plus operating mechanism is another to check.

There are no rumbles or rattles and it runs very well. What else would you do while it is out?

Geoff

[Jon Tilson]

Oil leaks and mounting checks. Replace rack mounts.
General clean up underbonnet.

Sure you dont need me to tell you...

You can get them out in about 3 hours. I think your Robert does it in less but he drops the whole subframe, which is another option if you have the tackle.

Jonners

[xvivalve]

I'll second the statement that you can remove the manifold in situ.

Manifolds were, I believe, helicoiled from new.

[MIG Wielder]

This is the 79 pageant blue Sprint I bought in early '99 and has done 30,000 trouble free miles since. I had to sort out the steering and suspension when I got it but have done nothing mechanical, other than a new clutch. Neither head or sump have ever been off. Anyway, the exhaust started to go so I thought as this is the car I will always keep, investing in a stainless unit would be the way to go. Old exhaust came off without issue but when tying to bolt up the new stainless twin downpipe the middle/inner bolt (new) started to just go round and round in the manifold. I can't see but it felt like an old (rusty) helicoil has given up and started to pull out.

I can't see any way of putting in a new helicoil in situ, there just isn't the room. I've got a kit the right size. Next I thought of removing the manifold, another job that isn't easy in situ as you can't get a socket on all but the front bolt - and you guessed it, I can't turn any with a spanner. Bolts look very rusty as you would expect so I've left them soaking in WD40 but whether that will work is debatable as it will be a long time since they were undone, if ever.

The next option can only be taking the head off, but heaven knows what trouble that could bring............

Any ideas or tricks I could use anyone? I don't want to dig this hole deeper than I have to.

Geoff

Hi Geoff; Is this an LHD or an RHD car ? I can't remember who drives which side these days.
If its an RHD car then my solution on DHO was to use a surface drive ring spanner on the exhaust manifold bolts , remove them as far as possible, and then gently drop the exhaust manifold against the inner wing.
In your case can you use a Dremel ( or other excellent tool) to grind the heads off the exhaust manifold bolts ?
You can then drop the exhaust manifold a lot closer the the inner wing ( Buffer the paintwork with a thick blanket )
You can then use an electric hacksaw to cut through the remains of the manifold bolts between the manifold and head.
Try and leave as much distance as possible between the head and manifold.
You can then lift out the manifold on an RHD car .
You then use a stillson wrench with lots of Plus-Gas to remove the remains of the manifold bolts.
If any remain stuck in then you are still down to a head off job.
Either way you will need 6 new long manifold bolts.
HTH.
Tony.

[gmsclassics]

First thing this morning I tried those manifold bolts and despite soaking overnight in WD40 none would budge. Decided in frustration to give up for the day and take the Jag out for a run. Still mid winter here, 14 degrees and possibility of rain in the afternoon. Still, sun out so off we went.
There is a 70 mile round trip from here that is a popular run with car and bike clubs, all on B-road, not a motorway or A-road in sight. Through a number of villages and then from Clevedon it hugs the coast heading south, past three coastal regional parks and a seabird sanctuary down to Kaiaua. We gave the fish and chip shop a miss and then the route heads back inland. Living 25 miles south of central Auckland we miss all the traffic that fortunately sticks to the main highways too intent on getting to their detination to actually enjoy the journey. Lovely uplifting day, open road with little other traffic, fabulous views, sun all day as the rain never came. Back home and an hour on the ride-on mowing the grass - could never get away with calling it a lawn!
I had been mulling over everyone's comments all day, so with a few hours of the day left, decided to have one more go. This based on Alun's comment that the manifold all came helicoiled from the factory. I wondered if I could get the old helicoil out as that would then mean, if I could use the tap from the helicoil set to clean up the thread, I might be able to put a new insert in. First I removed the heat shield to maximise access, then using a 3/8 UNF bolt, managed to catch the thread. Eventually I got an end pulled out then, with remaining fingers crossed, gently pulled until the entire insert unwound and came out. Then managed to get the helicoil set tap to bite. Only way I could get it to turn was using a 1/4 spanner, quarter of a turn at a time. Took ages. After that the new insert went in easily. Cleaned up the other two threads and following Jon's suggestion, found a couple of suitable studs in my box of old bolts and nuts and put them in the top two threads. With the heat shield removed the new downpipe fitted easily - in fact I suspect all it would have gone on three as studs, but I could only find two!
So now all firmly attached. I still have to put everything else back, but at least the main problem is now fixed. Thanks all for your advice and comments, a good outcome. Funny how some days just seem to go well.

Geoff

PS: Tony, RHD in NZ and Aussie. Good thing as a lot of classics here arrived as second hand private imports from UK. Still goes on a lot even now.