It All Started with the Windshield Seal...
Part 2 - Head Rebuild
We had a crack in our exhaust manifold, and the new replacement
manifold is insanely expensive. We decided to try welding the
crack for the time being, we'll see how long it lasts. We welded
as much of the crack as possible with the manifold still bolted to the
head, then pulled it off to get the less accessible spots. The
gasket was also leaking, so we have a new one to replace it
with. With luck, these are our last exhaust leaks & we
should stop backfiring!
Due to the high price of the 404 specific exhaust manifold for the
M180 engine, we're exploring the possibilities of modifying things
enough to fit the exhaust manifold from a sedan. Click here to
go to a separate page with the many pictures of our "Exhaust
Inspection of the ports with the manifold off revealed reasonable
looking intake ports, and gooky exhaust ports. The exhaust ports
on cylinders 1 through 5 looked reasonable, port number 6 looked
absolutely disgusting! Looking in further showed oil running
down the exhaust valves - yuck! So, the head had to come off to
get the guides replaced... our two weeks to get the chassis ready for
cab replacement just got extended! However, this should solve
the slight smoking issue we had been having.
Removing the valve cover is so much easier with the cab off!!!
We're looking forward to adjusting the valves before we put
the cab back on. Should be the easiest adjustment yet.
Headless engine and head on the bench.
Cylinders 6 and 5, number 5, numbers 5 and 4, and cylinder number
1. 5 and 6 were the goopiest. Number 1 was pretty
dry. All of the gunk was very soft, it scraped off very easily
and then we sucked it up with the shop vac.
Here's the underside of the head.
Combustion chambers 5 and 6, and 4 and 5. 6 was thoroughly
black. The rest looked a lot more reasonable. When the
machine shop cleaned up the head, they found water damage in 5 &
6. There were cracks in the water jacket between these two
chambers. They've been welded & the surface planed (see
In the interest of spending as little money as possible at the machine
shop, we wanted to disassemble the head as much as possible
ourselves. At first we were a little stumped, we've never dealt
with an overhead cam before! The spring compressor we had in the
drawer definitely would NOT fit in there to do the job. Ken
remembered having received (free tools are great!) a spring compressor
he hadn't quite figured out how to use.... sure enough, it was
for an engine with an overhead cam! Once we figured that out, it
was a few hours work to get the valve train apart.
Here's a shot with two rockers off. We removed all the rockers,
then proceeded to remove all the valves.
At this point, we weren't sure how much more would have to come off to
replace valve guides (we didn't know yet that the head would need
welding), so we chose to take it to the machine shop like this.
A nice little collection of valves.
Can anyone identify what is different about the valve stem on the
Shiny "new" head back from the machine shop.
Closer shots of the cylinders in order. Note that cylinders 6
and 5 are badly pitted from water damage. Head was welded &
Here is the top side of the head. The machine shop couldn't seem
to locate new exhaust valve guides the right size, so they
manufactured them themselves. (In retrospect, one of the MOG
dealers could likely have gotten them for us & saved a lot of
effort, but we didn't know the machine shop couldn't find them until
we picked the head up with the work done.)
Valve stem seals were not available in Canada! MB in Toronto had
10 in stock (useful number...) the remaining two would have had to
come on a slow boat from Germany.... so we ordered them from
Scott. Once they arrived it was on to head assembly.....
We just can't resist the comparison shots with VW parts! Up
until now, they are the only engines we've dealt with, so the contrast
can be rather interesting.
Here's the "new" head, assembled and ready to go back on the truck.
The head is back on the truck & ready to go!!! The valve
adjustment was awfully easy with no cab parts to get in the way.
Return to Part I