1984 300DT: water pump gasket question.

[HuskyMan]

In the process of installing a new OEM mercedes benz water pump on the 1984 300DT (photo attached). Should I use Permatex Anaerobic Gasket Maker on both sides of the new gasket?

[sixto]

I don’t have a manual with me but I expect it’s spec’d to go on dry.

I use Permatex ultra gray RTV on every flat gasket.

Sixto
98 E320s sedan and wagon
02 C320 wagon

[luketmarx]

Yes both sides.

[tyl604]

I see no clear answer here. About two years ago I put a new one on my '81 300SD and did it dry. Have had zero problem.

[bigpanda16]

If you clean the surface well, you needn't any sealer, just the gasket

[Diesel911]

If the Water Pump Housing screws are exposed to the Coolant; meaning the holes are drilled all the way through you need something to seal the threads so coolant dose not seep past the threads.

Never tried a dry gasket on any water pump (pessimistic).

On Water Pumps I use the old school in a tube brown non-hardening Permatex that was around since at least 1950ish. It is extremely reliable but messy.

I had an issue using RTV-silicon one time. While I wiped off the sealing area on the block I did not degrease it. The RTV-silicon did not stick to the oily part and it rusted under the gasket and leaked. The Permatex does better in a less sterile environment.

The hardening permatex would also work but it is a mess to scrape off later.

[tyl604]

I still vote for dry. If the MB engineers spec'd it that way, it is good enough for me.

So looks like just personal preference.

I am still unhappy that I replaced a perfectly good 37 year old water pump thinking that it was the source of my noise when it turned out to be the AC compressor.

[HuskyMan]

I just purchased permatex spray-a-gasket. I'm going to spray both the mating surfaces and both sides of the gasket as well as the threads on the water pump bolts with it. We'll see how it comes out......



https://www.amazon.com/Permatex-80065-Gasket-Sealant-Aerosol/dp/B000HBICK2/ref=sr_1_2?crid=16SISQ4026YJE&keywords=permatex+spray+sealant&qid=1551053322&s=gateway&sprefix=permatex+spray%2Caps%2C177&sr=8-2

[tyl604]

Remember the days when we took a brown paper bag from the grocery store and made a gasket?

[HuskyMan]

Does anyone know the torque specs for the water pump bolts?

[tangofox007]

Pump to pump housing bolts is 10 Nm.
Fan clutch to pump bolts is 20-25 Nm.
The FSM does not specify the use of gasket sealant on the pump-to-housing gasket.

[okyoureabeast]

Don't put the gakset goop on. Did that once and only once for the reason why the engineers didn't say you needed it. When it starts leaking you'll be cussing.

[t walgamuth]

I do it dry if the factory says dry.

When I first started driving benzes the life expectancy for a water pump was only 30 to 40,000 miles. Now it is a rare failure.

[Mike D]

Unless the mating surface is damaged then dry is the way to go.If you do use a silicone sealant then remember, "Thin is in". Just the slightest wipe of sealer.

Nothing like having a blob of silicone floating around until it clogs a passage.

You older fellers probably remember "Indian Head Shellac". It is now made by Permatex and doesn't quite have the "welded together Forever" properties the original formula had. My dad used to swear by the stuff. I used to swear at my dad for using the stuff. It sealed all right. It sealed the parts together! Following his work was a test of perseverance. Nothing, and I mean NOTHING he put together ever came apart without an hour or two of prying, soaking, cussing and cleaning.

Made me a believer in the adage, "Gasket sealers are for beginners. The experienced know that proper cleaning, preparation and tightening is the correct approach".

I do use the Permatex High Tack gasket cement for those gaskets which simply won't stay in place in a confined access area. Works a treat for sealing battery terminals also. Seals air tight and is water resistant. Cleans off with just a spritz of cleaner.

http://www.curbsideclassic.com/blog/history/cc-toolbox-indian-head-gasket-shellac/

[Mike D]

Originally Posted by tyl604

Remember the days when we took a brown paper bag from the grocery store and made a gasket?

Amateur! Everybody knows you're supposed to use the cardboard from a cereal box!