W126 Bonnet insulation

All W126 models have an insulation pad under the bonnet to protect the paintwork and reduce engine noise.     Over time, the W126 bonnet insulation degrades and starts crumbling down onto the engine.    At this point most owners simply remove it.

I own two W126 models with the remnants of their insulation pads.   A few months ago, I purchased W126 bonnet insulation to fit to both of the cars.   It is worth noting here that the coupe insulation pad is different to the sedan.   I also purchased some Selleys Kwik Grip gel to glue the pad to the bonnet.   It apparently works in high heat environments and spreads easily.     I got the 800g tin.   In the end I found I needed 1.5 tins.

The first step is to scrape off the remains of the old W126 bonnet insulation.

W126 bonnet insulation

I used an old sheet to catch all the ‘crumbs’ and a plastic scraper to get as much off as I could.     Next is to line up the new pad to see how it would fit.  I kept the sheet in case I spilled any glue.

W126 bonnet insulation

The pad is slightly molded to conform to the underside of the bonnet.   It also tucks in at the bottom, and a little bit at the top and sides.   I applied a liberal amount of the gel to ensure it sticks properly.   The gel came with a spatula and I had a little brush, but I actually found using my hand (with a glove of course) as the easiest way to spread it.

W126 bonnet insulation

Using my hand allowed me to get into the corners a bit more than with the spatula.   As mentioned above, I found one and a half cans seemed to be enough.    Putting the W126 bonnet insulation on is possible with one person, but would be easier and neater with two.   I didn’t have an assistant and found it was easier to start at the bottom and tuck those sections in before attending to the top.   The picture below is poor quality, but is attempting to show the new pad on the car.    Note there are two little rubber blocks on each side that need to be removed before the pad can be attached.

W126 bonnet insulation

In addition to the W126 bonnet insulation,  last week I had the flexible drive couplings (flex discs) and the motor/transmission mounts replaced.   I didn’t have the time to do it myself.    The mounts require the engine to be jacked up and are quite fiddly.   All of those things should improve the way the car drives and make it much nicer.   Certainly it runs very smoothly now with the new timing chain and mounts.

If this glue works well, I will use the same method on the 300SE.

Update August 2019:  I was happy with the results from this job that I used the same method on my W126 Sedan.

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