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Engine mount bolts
Posted: Wed Jul 22, 2026 9:57 pm
by Grumpy21
What do people do with the awkward engine mount bolt the sits at the junction of the front crossmember and chassis leg. Can’t get a spanner or socket on it. Mole grips jump off. Had to drill it out but wondering what to put back in. Current thinking is cap head!
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 10:22 pm
by svenedin
You mean the bolts for the engine mount towers, 4 bolts each side?
The nuts and bolts are 5/16" BSF x1" so you need 1/4" Whitworth spanners. You need a spanner to hold the bolt and another to undo the nut so it does help to have 2 sets of Whitworth spanners. I don't recall the job being difficult with combination Whitworth spanners, using both the ring and open ended jaws.
To actually remove all of the bolts only 1 per side may be awkward as it is prevented from coming out by the tie rod. The tie rod needs to be undone and moved out of the way.
Stephen
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 10:54 pm
by Grumpy21
Yes I’ve got all the tools to do the job and some!
And yes it’s the pedestal bolts I’m talking about. 3 come out easily but the one in the corner is a swine. Done the job twice on two cars now (so 4 x bolts) and every one has fought me all the way. From underneath you can’t get a ring spanner on as the chassis rails are too close, can’t get a socket on for the same reason. Can’t grip with an open-ender as it’s in a corner, same with mole grips etc.
Last time I welded a 7/16 af nut onto the 1/4 whit bolt head so I had something to grip when tightening
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 11:04 pm
by Grumpy21
Best pic I can find
Bolt circled in yellow at the bottom
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 11:09 pm
by svenedin
Grumpy21 wrote: ↑Wed Jul 22, 2026 10:54 pm
Yes I’ve got all the tools to do the job and some!
And yes it’s the pedestal bolts I’m talking about. 3 come out easily but the one in the corner is a swine. Done the job twice on two cars now (so 4 x bolts) and every one has fought me all the way. From underneath you can’t get a ring spanner on as the chassis rails are too close, can’t get a socket on for the same reason. Can’t grip with an open-ender as it’s in a corner, same with mole grips etc.
Last time I welded a 7/16 af nut onto the 1/4 whit bolt head so I had something to grip when tightening
I will have a look under my car tomorrow. I just don't remember it being particularly problematic. I think I used an open ended spanner and if that wouldn't fit well on the head of the bolt due the way the hex was orientated then I undid the nut on the other end until the bolt started to turn and I could get the spanner on properly.
Do you mean the one arrowed in my picture? If so, open ended spanner worked for me.
Stephen

- IMG_8857.jpeg (1.43 MiB) Viewed 1415 times
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 11:23 pm
by svenedin
Ah I see your picture now. If an open ended spanner won't fit, undo the nut on the other side until the bolt head starts to turn and the hex is orientated in such a way that the spanner fits. If the hex doesn't turn at all and is seized, just undo the nut completely and knock the bolt through.
Stephen
Re: Engine mount bolts
Posted: Wed Jul 22, 2026 11:41 pm
by Grumpy21
Nah, that certainly doesn’t work.
The one under the tie bar is dead easy it’s the corner one that’s awkward. Because it’s right in the corner only the very tip of an open ender will get one, not even half way, even when it’s rotated. Then either the spanner jumps off or the head deforms and it’s so tight to the chassis a ring or socket won’t go over. In all 4 cases I’ve had to drill the heads off the bolts.
Im inclined to refit using cap heads so the next man will have an easier time should they need doing again.
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 7:55 am
by Sleeper
A couple of things , every little helps...
Get rid of washers and replace with these stainless....and cutting a screwdriver slot helps...

- mountsc.jpg (157.7 KiB) Viewed 1180 times
Get rid of washers and replace nuts with these

- mountsa.jpg (169.28 KiB) Viewed 1180 times
John ;-)
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 7:56 am
by Sleeper
P.S.
also helps to " slot" the mounting holes "
Sorry Purists.
John ;-)
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 8:02 am
by Grumpy21
Morning, the awkward one isn’t in your pics (the only one not in the pic) and the problem is from below not above. I can easily access all the others. It’s bolted from below but too close to the corner of the chassis rails to get a decent grip on the bolt head.
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 9:08 am
by svenedin
I'm getting the car out this morning anyway so I'll have a look underneath. Not that it really makes any difference but last time I removed the bolts concerned and reinstalled them, I had the front panel off the car and access was very easy. I could just sit on the floor in front of the car and reach in.
Stephen
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 10:22 am
by svenedin
I just had a look and I see the bolt you mean. I agree a ring spanner will not fit on the hex but I could get a 1/4" Whitworth open ended spanner on it well enough. I couldn't take a picture of the spanner on the hex as I don't have enough hands!
Surely if you absolutely can't get a spanner on it you can just jam it and stop it turning with a screwdriver or something?
Stephen

- IMG_3593.jpeg (2.19 MiB) Viewed 1120 times
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 11:02 am
by Sleeper
Do you have access to a drill and MIG/silver solder ?
If so , I'll show you the other method I've used , in this case No 5 bellhousing bolt.

- captive nut screw1.jpg (161.73 KiB) Viewed 1105 times
You can do this to either the screw or nut ( but not both

)
John ;-)
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 11:24 am
by svenedin
Possibly a 1/4" WW box spanner will fit. I have one somewhere.......
Stephen
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 11:46 am
by philthehill
Cap headed bolts are the way to go.
Re: Engine mount bolts
Posted: Thu Jul 23, 2026 4:25 pm
by Grumpy21
I have MIG and considered welding a square washer to the bolt head but decided cap head is the way to go. I can’t get a socket on the bolt head otherwise there’d be no problem. Neither can I get my open ended more than half way across two flats. Maybe my spanner’s are too fat?