cmac2012

I’ve had phantom cooling loss for some time. I searched the system quite a bit, needed new freeze plugs, the radiator had a small leak, the cap was not in good shape as well. Fixed all of that, I’m still losing fluid, no dripping on the ground.

I’ve had some white smoke on start up for a while. A professional mechanic on my Benz forum told me that the SBCs have a weakness in the intake manifold area, and that sometimes a problem there would look like a bad head gasket, and then clear up upon warm up, which is sort of what I was seeing. Never had coolant smell in the exhaust once it was warm, or cold for that matter.

I had the time and space to dig into it in the last couple of weeks so I decided to put in new intake and valve cover gaskets.Upon draining the coolant, I saw it was all bright green. I drained the oil, word was you will likely spill water in the valley when you take the intake manifold off, so best to drain the oil, then you can drain the water and do a small flush on the pan after.

The oil also did not show signs of a head gasket blown. I experienced that on my Benz 300SDL. Blowing steam full-time, it quit soon enough. Luckily, I found a low miles engine and tranny through my mechanic, also an OM603 fancier.

He dropped that in, and suggested I take the head off of the old motor, they can be hard to come by. I did, and there was the bad head gasket. Not real dramatic to look at, but obviously not Primo and I had seen the results in real time.


Has been a pretty big job just by itself. I almost wish I could’ve gone the full route and had the heads re-done, but time and money was getting in the way.


Both valve covers had a lot of caked on grease/oil, and it looked water contaminated:



The intake gasket didn’t look good, and the two stud bolts up by piston number one twisted off. Another friend suggested that might be an indication there was some leakage there, and they are at a water port.

I didn’t freak out too bad when it happened because I knew I would have the remaining fragments sticking out above the block - sure enough, I was able to twist them out with vice grips and a blow torch.

Luckily, I found those two bolts, the only studs among the 12 intake bolts, at a boneyard. They looked pretty good. I couldn’t find suitable replacements at the auto parts stores. Getting new originals probably would’ve cost a few pennies and taken a while.

There was also a lot of corrosion in the bolt holes in that part of the manifold. Apparently the residue of steel corrosion as the aluminum in the holes seemed fine, thank God.

I have it almost all back together, a couple of questions are presenting themselves, maybe someone knows about these things.

My serpentine belt is degrading on both edges, one worse than the other. I replaced it two years ago, the broken one had similar damage. The idler pulley feels a bit sloppy. I wish I’d notice this sooner, I don’t have time to get a new pulley now. I need to leave in a couple of days back for the Bay Area. With any luck I can put it on with the radiator in place.

Also, there is a fitting, it looks like a vacuum line, not sure, off to the side on the right of the engine bay. I don’t recall unhooking it, I didn’t label it. On the other end it’s connected to the lower, smaller line on this canister unit which is to the passenger side of the engine bay just behind the grill. Not sure what that is. I can’t find any obvious home for the fitting. Anybody know?




Any feedback on the rest of the job is of course, welcome.

mountainmanjoe

It might help to post your vehicle details, please and thanks.

mountainmanjoe

probably the vacuum reservoir. It should lead to a 'T' where one end goes to the intake manifold and the other through your firewall to the HVAC system.

cmac2012

Oops.

1989 G20, 5.0

193k on the clock. Acquired it at 119k, was pretty strong. Had to put a new distributor in at about 150k. Or, rather, my mechanic did. It was stalling at stop signs, stop lights, I could not find the problem for the life of me. I put on a new cap and rotor, didn’t think to check the distributor itself.

Nothing major aside from that. I rebuilt the throttlebody injector also at about 150k. New starter about 170k.

cmac2012

Well this is definitely not good. I put it all back together, it started up pretty well, it’s making one funny noise but I don’t think it’s deadly. Sounds peripheral. The real problem is the temperature gauge steadily rises. I shut it off at about 60, 70%.

Then I noticed that the return hose was flaccid and cold. I drained the radiator to have a better look at things, the water was cold. I am praying that it’s some weird burping issue in the cooling system, it’s something very easy to fix. I put in a new thermostat.

I put a new water pump while I was at it. No idea how old the existing unit was.

First step is to pull the thermostat housing off.

cmac2012

Turns out it was indeed merely an airlock getting in the way of proper cooling. I took the thermostat housing off. There was no coolant in the intake manifold underneath. I put it back together without the thermostat, used some RTV. The radiator is getting warm like it should. I’ll put the thermostat back in today.

But I’m not out of the woods yet, there is an odd and unsettling flapping noise, sort of like a playing card in bicycle spokes. I don’t think it’s something horrible in the block or heads, the intermittent aspect of it as well as the light sound points to an accessory (he said, optimistically). I have a mechanic’s stethoscope back home, I’m at my sister’s place in Washington, I might go buy one to try to find the source of the noise. Here is the sound:

https://youtube.com/shorts/CHOkylzGT9M?feature=share

I replaced the alternator in 2017. I noticed the AC compressor was cycling on today. Turns out it was on defrost, the web instructed me that it will frequently run on defrost, I had forgotten about that, I looked inside, it turns out I had it on defrost.

I touched the top of the compressor, completely smooth. It’s not the fan blade hitting the shroud. You can see at the end of the video I pushed the shroud down a little bit. Different sound.

mountainmanjoe

take the belt off and see if the noise goes away

cmac2012

excellent advice. I should’ve thought of that.