[P38] Exhaust gases in coolant

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
Afternoon all,

I bit the bullet and decided to try my hand at getting the heads off myself.

20250302_154446-2.jpg


All was going very well, until...
Those bast*rd exhaust heat shield bolts. 16 of them total, and only 2 have come out.
The rest of them are seized and rounded, result of another handyman's work it seems.
It's the only thing between me and those exhaust manifold bolts, and finally getting the heads off!

Has anyone dealt with this before, and how did you get round it?
I've got extractor bits but I'll never get my drill in there.

Thanks
 
Thanks for your replies.

I could maybe try and hack the top ones off, but access to the bottom ones might be a bit tricky.
Car is on it's arse right now, so not really any room to get underneath or under the wheel arch lining.

I'll try the brutal methods tomorrow once my hands have healed a little.
 
I think i just wrenched until some bolts snapped and off they came. My shields pretty much fell apart with corosion anyway, so I don't think I could have refitted them anyway. I'm pretty sure I've read of people taking the heads off with the exhaust manifolds still attached, but I've never done it myself. At least you'd have better access to the rounded bolts that way.

There is a cross member runs along the front by the bottom of the rads you can get a jack on if you need to lift the front at a pinch.

I wouldn't leave the car jacked up for ages like that, but it might get you some room if you need some....
 
MrGorsky said:
I think i just wrenched until some bolts snapped and off they came. My shields pretty much fell apart with corosion anyway, so I don't think I could have refitted them anyway. I'm pretty sure I've read of people taking the heads off with the exhaust manifolds still attached, but I've never done it myself. At least you'd have better access to the rounded bolts that way.

There is a cross member runs along the front by the bottom of the rads you can get a jack on if you need to lift the front at a pinch.

I wouldn't leave the car jacked up for ages like that, but it might get you some room if you need some....
Click to expand...
Silly question, but aren't the exhaust manifolds bolted to the cylinder head itself? Or do you mean they unbolted the manifolds from the lower end and pulled the lot out all at once?
 
I think they're just bolted to the heads, not the block. So if you take all the head bolts off the manifolds can come off with it. You have to unbolt the exhaust at the other end though where it meets the O2 sensors bit...

I'd like a second opinion really. Like I said I'm pretty sure I read about someone doing that once, but I've never done it myself!!
 
The problem is the manufolds obscure the head bolts. When I did my engine rebuild, I cut away the flange to allow access to the bolts in future. The bit cut off doesn't make any difference.

For the manifold they need a decent 12-point socket. Thye oly other option is to use an Irwin Extractor on them.

1740935406963.png
 
For those heatshield bolts i just used a pair of plumbers pliers while lying under the car. Some ended up coming out, most just snapped off. Honestly i was glad if i could get them to snap because it meant less unthreading to do.
Thinking about it now, if i had to deal with those ****s again i would just tighten them till they snap.

With regards to the heat shields i refitted the inner ones(between the manifold and block) just to keep some of the heat from radiating back onto the engine block. I threw the outer ones away and just put a nice thick layer of exhuast wrap.
Sidenote: when wrapping the manifold do not wrap over the flex joints, it shortens their lifespan quite drastically due to the extra heat. It also helps if you wet the wrap and keep it wet while wrapping, just makes for a way more pleasant experience.
 
When I put my manifolds back on, I replaced the triple square things with normal high tensile bolts I think. Is there an advantage to using the 12 point star thing?
 
Today's update.

Slow progress, managed to get the top exhaust manifold bolts out purely just by mangling the heat shields out of the way. The tricky part now is getting the lower ones out, access from underneath is pretty impossible.
My mangler, an 18 inch masonry chisel, has proven useful but I don't think it can do much more.

I also snapped the head off of one manifold bolt - I hope the machine shop can take care of that.

Also quick question- are the head bolts SAE or metric? I've been switching between both like a yoyo while doing this teardown.

I'll keep trying tomorrow! Slow and steady is the key.
 
Last edited:
I just used a metric 12mm 12point socket, worked okayish without any issues.

IMG_20250303_200338.jpg

Another mod i did that i would recommend is to cut the section of steel on the manifold that joins two of the exhaust ports.
My brother and i both had manifold sealing issues where the two ports would not be parallel, this whole section of steel had a slight bow to it. So we basically just cut that section of steel that joins two of the ports together to allow each exhaust runner to move independently. We haven't had any manifold sealing issues since doing this.

Something else ive been contemplating doing is to change the manifold bolts out for studs or possibly capscrews, the studs i like because almost no chance of damaging threads in the head. The capscrew idea i like because itll be way easier to get an allenkey instead of a socket into the manifold bolt on the righthand header closest to the firewall.
 
You must log in or register to reply here.

Similar threads

P38 Monkey
P38 4.0 GEMS 1997 - exhaust gas in coolant
Replies
2
Views
868
Mark Piercy
Mark Piercy
Intestinalworm
Disco 2 Head Gasket and Heater Core
Replies
11
Views
2K
Intestinalworm
Intestinalworm
htr
Freelander 1 HTR - hacked off :(
2 3
Replies
42
Views
4K
htr
htr
A
V6 Overheating, please look at video
2
Replies
25
Views
7K
Nodge68
Nodge68
chrisall69
another p38 overheating
Replies
12
Views
4K
sandyt
S
Back
Top