[MBGraham]

Slowly getting pump face cleaned up. Hard to get the yellow scale out without damaging the seal groove in aluminum - but getting there. While at it, opportunity to clean most of grease that covered front of engine and sump.

In looking at bolts that were troublesome to get out, they have rust on the threaded area. So water or coolant got down through the threads. One of the long M8s is rusted along entire length. Many of the bolts are close to the edge of the seal groove indicating seal may have leaked a little (although no signs of leakage). Or water penetrated from outside (blown in through rad?

Question for Witek/Deplore and others: Would it make sense to apply some thread sealant to the bolt threads near the head end? Just far enough in to stop water entering the threads?

I have Hi-Temp thread sealant shown in picture below. Pictures also show two of the more rusted bolts that didn't break.

Not my picture, but this show where those two rusty bolts were. The long M8 (lower) passes through and threads must be inside on block? Wherever, water must have got there!

 

[Deplore]

I don't live in rusty area, so I can't be much help, but as long as that thread sealant is not a threadlocker in any form, should be ok. Dielectric grease works too, but only at the very top of bolt. Or brake paste.

 

[MBGraham]

I have this stuff, so will try it. Specs seem OK:

Permatex® High Temperature Thread Sealant, 50 ML – Permatex

www.permatex.com

I want to pressure test after assembly with water before adding coolant. Our local HF type store has pressure testers on sale - But no stock locally and no way of knowing if their adapters will fit

Next and cheapest idea was to use my pressure brake bleeder (I have used it on boats for this purpose). But I need a cap. Local stores - no stock Parts store getting me one by Monday!

 

[mrboca]

I used HF radiator pressure test kit. One of the adapters fits perfectly. That is how I found out my coolant pump was leaking under.

 

[MBGraham]

I used HF radiator pressure test kit. One of the adapters fits perfectly. That is how I found out my coolant pump was leaking under.

We don't have HF here, and beside US$89 is a lot for a one-time test. Our Princess Auto HF look-alike were out of stock, but otherwise I would have bought one on sale for C$43.xx
As it is for C$18, I will get a cap on Monday and modify to use with pressure brake bleeder.

 

[MBGraham]

Mounted the pump today. Ran into a small problem that I thought I should document here in case others run into same issue.

I had bought new M6 bolts from dealer (7 short 3 long) identical to originals. I had a problem with the longer ones - They "appeared" to bottom out. I could get a fair size feeler gauge under the head. This did not happen using an original bolt. Depth gauge showed more than enough depth in holes.

So why did the new bolts appear to bottom out?

I think Witek said that the bolts were self tapping? (Nothing about them would make you think that!) However, perhaps the original bolts when first threaded in slightly deformed the threads in the timing case and the new bolts were hitting against that?

Based on that theory, I ran an M6 tap carefully through the three problem holes. The new bolts now go all the way in!

 

[Witek_M]

If you roll those bolts in your fingers you will feel (I do) that they are not perfectly round but rather tri-lobular shape.

 

[MBGraham]

If you roll those bolts in your fingers you will feel (I do) that they are not perfectly round but rather tri-lobular shape.

View attachment 2814813

Thanks! I wondered why they called them tri-lobular. I wrongly thought it was to do with the head. I will measure the new bolts. They came from the dealer, but perhaps replacement bolts don't have those sharper end threads? Tapping through resolved the issue.

The new bolts have a grey coating. Some of the longer removed bolts have a blue coating on the threaded area. Any suggestions for the new bolts and for the re-used bolts? I have them all in hand tight, but perhaps should remove one at a time and add an anti-seize/sealant before torqueing?

 

[Witek_M]

In parts catalog they are called hexalobular and that indeed refers to bolt head. MB does not use Torx designation because that is a trademark.

 

[SocalSam]

I have this stuff, so will try it. Specs seem OK:

Permatex® High Temperature Thread Sealant, 50 ML – Permatex

www.permatex.com

I want to pressure test after assembly with water before adding coolant. Our local HF type store has pressure testers on sale - But no stock locally and no way of knowing if their adapters will fit

Next and cheapest idea was to use my pressure brake bleeder (I have used it on boats for this purpose). But I need a cap. Local stores - no stock Parts store getting me one by Monday!

You can make your own test cap. Get a reservoir cap from the JY. Tap a nipple and run line to compressor. Compressor will need line gauge.

 

[MBGraham]

As mentioned in post #105, I have a cap coming tomorrow. No Junk Yard here with Mercedes parts! No new caps either, but at C$18 delivered, no big deal. I will use same device that I have used on boat cooling systems - my home made brake pressure bleeder that I can pump to any pressure I choose! (I used same kit to test my Djet injector flows Kind of multi purpose tool )
Plan is to fill with water for static pressure test. If no leaks re-install belt and run engine for short while. Finally drain water which should also provide a rudimentary flush

 

[SocalSam]

After 100 plus posts, I will assume you are just as meticulous with your installation. I would trust the work and go for it but that would not be your style. And you would lose sleep, lol.

 

[MBGraham]

After 100 plus posts, I will assume you are just as meticulous with your installation. I would trust the work and go for it but that would not be your style. And you would lose sleep, lol.

When it is -3C in my garage, as it is today, I tend to stall as much as I can. While stalling, I get some great tips on-line from those who do this for a living! But, heading out there right now! No rush

 

[mrboca]

The middle of the radiator cap has a pressure relief valve. Also the neck of the reservoir has a hose connected to it to remove the excessive air / coolant pressure. How will you modify the cap to apply air pressure?

The radiator pressure adapter that came with the pressure kit fits into the opening in the neck below the pressure release hole, so the pressure relief function is bypassed.

 

[SocalSam]

OK, not easily done. I try not to buy test kit I will likely use only once.

 

[mrboca]

OK, not easily done. I try not to buy test kit I will likely use only once.

This is something MBGraham needs to figure out . Some auto parts retail shops rent / loan Pressure test kits . The same test kit is less than 40 bucks in Amazon. You can use the pressure pump in many other applications .

 

[MBGraham]

OK, not easily done. I try not to buy test kit I will likely use only once.

Actually not that hard really. MBoca is concerned about what is already in the cap. But that can all be removed. Cap then used to hold an adapter (that is still to me made!) in place We will see how this goes.

 

[mrboca]

Actually not that hard really. MBoca is concerned about what is already in the cap. But that can all be removed. Cap then used to hold an adapter (that is still to me made!) in place We will see how this goes.

Looking at the old cap that I happened to have, I think you can punch a hole into the check valve to let air go to the expansion tank from the overflow port. Maybe you can remove the rubber overflow hose, and adapt a hose to the port and connect the air pump to it.

 

[SocalSam]

Assuming a cap can be gutted and sealed, a standard threaded fitting and air hose should be enough. I think a tire valve would also work. My cheapness is starting to show. Time to call it a day.

 

[MBGraham]

Looking at the old cap that I happened to have, I think you can punch a hole into the check valve to let air go to the expansion tank from the overflow port. Maybe you can remove the rubber overflow hose, and adapt a hose to the port and connect the air pump to it.

Right - I was thinking of connecting air from brake bleeder via the overflow instead of drilling the cap. Haven't checked it yet, but perhaps if one seal is removed, that is all that is needed? Otherwise I will make an adapter for the cap.