Replacing head gasket 300sd, hot engine
 

Has anyone replaced the head gasket on a 300sd turbo diesel? I want to know if I'll need any special tools or if there is a special procedure or if there are some smart short cuts. I'm wondering if I can leave the timing chain on while I do it. Any suggestions or comments appreciated.

The reason I'm looking into the procedure to replace the gasket is I'm beginning to think mine is blown and creating the current running hot situation. I've replaced the water pump, thermostat, Cap, had the radiator professionally tested for flow, pressure tested the system. The car does not use coolant or visible leak it. It holds pressure. THere is no visible oil in water and vice versa. There seems to be no blockage in the system and the last time I back flushed it, the fluid seemed the right color and no sign of rust or contamination.

I just need to make sure it is the head gasket that is blown before I replace it.

Any suggestions or comments appreciated.

Tell us more about what constitutes your running hot situation. So far, I don't see any evidence to think you have a headgasket problem. Have you burped the system to make sure the air is out.

Any bubbles showing up in the coolant with the engine running? Clutch fan still good?

Although the radiator can pass the internal flow test, the real question is how much air can flow through the 20 year old fins. The main culprit of these systems is accumulated dirt and debris that clogs the air passages. You can see this debris if you remove the radiator and hold it up to the sun. The clogging will be obvious if it's present.

The best way to remove it is with a commercial condenser cleaner and compressed air..........it's a time consuming job.........but necessary if you want to reduce the operating temperature.

When I replaced my otherwise fine looking 22 year old original radiator (had just begun to leak at the upper tank seam)....my hot-day driving temps went from 95-100C, to 85C, and when its below 75 outside, it struggles to go much over 80C.

New radiator makes a huge difference. And WAY easier/cheaper than messing with the headgasket.

A simple way to make extra sure your headgasket is ok is by sending in a sample of your engine oil at an oil change to Blackstone labs, they will tell you if anything suspect (such as coolant) is in the oil....then you'd have cause for worry.

reply to replies
 

Guys thx for the fast responses. I am still a novice when it comes to mechanics. Please take that in to consideration.

I have not done any tests so far for the head gasket being blown. I will pick up my radiator from testing tomorrow. They said it check out good and it's a very reputable shop.

And...to answer your questions in order.

My car has been progressively running hotter by the month. I have not "burped" the system of air. How do you do this???

No bubbles in coolant while engine running. Clutch fan is in question.

Is there a test to check the Clutch Fan?


And about the external air flow through radiator...

That is a possibility. There is some build up in there. Would a hot tank method be possible?

Tell me more about this commercial cond. cleaner. Can I rent one??

Thx for the replies

Initially I was looking to replace my radiator but gave up after not being able to find a new one except for the dealer and they wanted like $1000.

My car is a 1980. Do you know of any places where they sell new radiators.

cooling woes
 

Daunting isn't it.
I really think mechanics sort of guess at this thing
Start w thremo & work there way around.,

I was running close to red line
replacing thermo thoug they said it was sticking didn't help
then it was sensor
that didn't help
Then new radiator

All in all those parts were close to 25 years old
(not sure if it was the origianl radiator) & its good to have new

but after all that it will run 95 to 100

Now thats an improvement but its not great.

they say its no problem still I;d like it to run specs
It is a Euro engine so it could run hotter????

That testing place sounds like a good idea.

In retrospect I'm thinking that the external fins of my radiator may have been clogged by the badly deteriorating hood pad that needs to be changed.
IIs this possible
I would suppose foam dust hitting a hot radiator would muck of the fins
thouigh it looked clean to the eye.

Nothing on water pump or head gasket yet

would assume those are the last?

Still its only had 2 runs since radiator change
& I would suppose there could be air in there


Will that come out on its own over time..

What about radiator cap?
It looks to be the orig MB 1.2 bar
Would that help to change???
Think only 140 psi or 1.4 bar is available now...

Good luck to all our hotties

:cool:

Did you refill the head when the radiator was changed?

The 140 cap provides a greater margin for boiling. It won't affect the engine temperature.

Did you shoot the head with an infrared testing unit to see if the gauge is accurate?

You may want to go the route I did. I found a used radiator for 80 bucks and then had it recored at a local shop. That cost me about $230. So for a little over $300 I have a good as new radiator.

No offense, but you should take into consideration the following:
#1 If you are having a cooling problem, and you're not totally sure its the head gasket, that would be the LAST thing to just jump into. Time consuming, and fairly detailed procedure, which leads me to #2
#2 If you are a novice, I would even think about doing that kind of job yourself. I've done LOTS of things to my car, including rebuilding the front end, entire braking system, electrics, etc, and I wouldn't even consider tdoing that job myself. Way too much room for engine failure if not done correctly...

Enrique did it
I wasn't there for the radiator change.
I did see him with a sort of temp gun aiming at radiator.
He said he found cool sopts in middle.

Guage did waiver so he changed the sensor as I was hopin g it was just a faulty reading but guess it was guess it was both as changing sensor did not make the oil temp read cooler.

I then left the car for them to figure out...
They changed the radiator & it now doesn;t go over 100 C
(before it got close to 120)

Only drove it twice since the radiator change
not sure if there could be air?

Then I thought maybe it couldn;t hurt to get a new rad cap if there is a possibility its that...

Thanks

Well, he ought to know how to get all the air out of the engine..............

The cap is a possibility if it's shot........not because it's a 120 cap. But, if it was NG, you probably would have overheated a long time ago.

Thanks,
So maybe the cap is ok

Just trying to tend to a new car that has had very limited use iin least 4 years
with a list of a few things
that seem to be having a hard time of getting resolved.

Don't want to look for more work

He has looked over the car twice
He even personally ran it up the hill of reseda
He says as lonf as it doesn't go over 100 C its ok

I think its high but at this point I'll just have to drive it more & see
To do that I need to get the mounting of the license plates issue resolved...

Thanks again.

Insurance got Vin to check out...
 

Well thats great news....

:D

Midday report:

Filter is clean flexible
I tapped it & there was some debirs
So I tapped it good
Also cleaned some sand & debris from under the filter.

Thats back on

then oopened exp tank
fluid was down about 24 oz
I added water
Its definitely the gold color
may not have been that before
there is a bit of residue floating

Then took off oil cap
clean oil no foamy crap
looked inside
Wow
a bright shiny piece in there
rods clean
rest is a slightly yellow golden color

Why is there no oil
Is top of head empty?
I can see inside all the guts
looks pretty clean to me

so going to get pics on top of head

Saw a broken rubber looking tube
its coming from what I think is the sruise control to the left of the warm up regulator???

well off to get pics of the inside of the head

its so pretty

:scream:

Good news maybw

checke coolant resovoir
it was down by about 24 oz

Guess the machanic didn't fill it all the way or there were air spaces.

Funny thing is coolant has sort of something floating on top
like a scum...

Good news is coolant is gold
but looks different than what I had in it.
Mine looked clearer..

Hmmmm

still hot...
 

Got it back together. The radiator has been tanked and tested, looking good. Replaced the Water pump too. While I was at it I replaced the front seal, which was leaking and the drive belts. Might as well do it now while I had it apart.

Still running hot up to 110 and over.
Used an laser temperature gauge to check if the gauge was reading reliably. Seems to be accurate.

Clutch fan seems to be working correctly.

Still holding water and passes pressure test.

Cap is nearly new.

I have not noticed any visible contamination of fluids, due to blown head gasket.

Tomorrow I will change the thermostat again. This time to the factory 80C specification. I think I may have put in a 87c before.

We'll see what happens.

Did you check the temperature of the head and the block? What were the readings? Have you burped the air out of the system?

Head temps at the time of test were in the high 90's, about what my gauge was showing.

What is the best way to burp the air out?

Point car uphill. Run car with heater on full blast for a number of minutes. Filling the system via the upper radiator hose is best way to avoid air in the system.

is 100c too hot in arizona climate?
 

Replaced the thermostat again. Drilled holes in it this time, got this trick off of diesel giant. Had issues with the housing sealing up right when I replaced the short 42mm hose. A nightmare. Electrolysis had pited some of the ends of the housing. Tried to find a used one but just waste of time. Finally I ended up J B welding it. Worked out fine. After getting back together again, still running 110c temps. So I went a bought one of those nice infared units.


these are my readings

Gauge said 110c when read
sending unit nut 101c
head around sending unit 102c
radiator next to top hose 100c
thermostat housing 95c


Is this too HOT?

Obviously my gauge is bad. will check for a bad ground when i have time.

Somehow, I doubt that this procedure was successful. The temperatures that you cite have all the indications of a radiator that is not doing its job. Either the external passages are clogged with debris...........something that a "tank" may or may not cure.........or the internal passages are clogged with corrosion........again........a hot tank may not cure it.

I'd be replacing the radiator right about now.........too much BS and no solutions.