Block Test Kit - Overheating 300SD - PeachParts Mercedes-Benz Forum

cousindave76 · #1 02-12-2011, 04:01 PM

Has anyone successfully used a block test kit on a 617 engine to check for hydrocarbons? The reason I ask is because the instructions for the kit I have found (NAPA kit) says to test from the radiator cap, but since there is not a radiator cap but rather a cap on the overflow tank, I was wondering if it could be tested from there? Also, what kit is recommended? I've seen lots of folks on this forum use the kit and post an "inconclusive" test result.

Why you may ask? If you're interested, continue reading below for the full scoop.

For the first 6 years of owning my 83' 300SD my temp gauge stayed rock solid on 80 degrees Celsius. I live in Dallas so I never hill climbed. But cold or hot outside, 80 degrees and that was it! A year ago I started having the engine temps rise. Now, in hot weather I cannot sit in traffic. The temp gauge will peg red if I let it. When it's freezing to mild temperatures outside, the temp gauge will balance out around 100 Celsius. I've gone through this forum and tried just about every thing. I've flush the cooling system with the soap and descale solutions. I've removed my water pump for inspection, it was fine. I've had three different 80c t-stats. No luck. I've tried many ways of burping the system... including having the front end tilted up higher than ramps can get it. It's burped. Recently I've read many posts saying the temp gauge is likely faulty. In fact, I see many OP's being told that is almost without a doubt a bad temp reading or faulty gauge. With that in mind I bought a an infrared temp gun and found that when my temp gauge is sitting on the 100 degree Celsius mark, the infrared showed the block at 98.5 Celsius. It's been really cold outside since I bought the gun and I have not had a chance to try it when my temp gauge gets REALLY high but I can be pretty sure that this mean when my gauge is saying my engine has hit 120, it is! So if you have a suspected overheating engine, don't let folks tell you it's just a faulty gauge and don't worry about. You MUST shoot the block with a temp gun to find out the facts or you risk blowing your head or worse. I've also checked my aux heater water pump, works fine. I've traded out my fan clutch, no change.

This brings me to the one last thing I can think of that might be causing my over heating. Blown head gasket. But due to the size of the job, I want to be sure. The engine runs fine. It warms up normally. The cooling system seems to be holding the right amount of pressure. I don't have a way of measuring the cooling system pressure but the upper radiator hose is firm and there is no antifreeze being forced out the overflow tank unless the engine gets really hot. The radiator is about 4 years old. The neck of the old one broke off while I was under way and the engine overheated at that time. That's one of the reasons I suspect head gasket. Perhaps overheating the engine a while ago weakened the gasket and now it is finally showing up? Thus, I really need to be able to check for hydrocarbons in the coolant to see if this is the problem.

Long post I know. But I bet many of you out there having this problem can understand the frustration and why I wrote so much.

HELP! If you have any ideas other than what I have tried above I am ALL ears

RAYMOND485 · #2 02-12-2011, 04:41 PM

1984 300D 156K TURBO
replace the radiator and refill with car front up diy.also r&r two radiator hoses

GregMN · #3 02-12-2011, 05:00 PM

If you run the defroster, does the temp go down? if so, check your radiator.

vstech · #4 02-12-2011, 07:09 PM

I've got one that does this. normal but for 120C peaks on occasion. I drilled a hole in the tstat and the temps stay rock solid at 80ish again.

charmalu · #5 02-12-2011, 11:35 PM

I was having a problem with the temp running higher than it should. Ihad replaced the engine with the new metric motor one. replaced the radiator, hoses etc... burped it also.
I was getting nervous seeing the gauge getting up there around 100. bought a Infra red temp lazer gun, shot different areas of the engine, and didn`t seem to bee too hot.
even changed the gauge, and bought new temp senders.

I read some where here on the forum of using a Thermostat for a SLC. think they are 75C. put it in and seemed to help some.

I did have a problem with the gauge later on, suddenly shoot up and peg at the top.

that will get your attention. Jump out of the car with the Lazer temp thing in hand, and start shooting the engine. discovered shutting off the engine, and restarting, the gauge would drop back to a normal range. sometimes turning on/off a switch would make it jump.

Discovered the ground strap from the engine to body wasn`t making a good connection. removed it, cleaned up the contact areas, and all has been well.

So check your grounds well.

Charlie

dieseldan44 · #6 02-13-2011, 02:45 AM

Dave, I have used this block test kit:

http://www.amazon.com/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76/ref=sr_1_11?ie=UTF8&qid=1297583029&sr=8-11

I successfully diagnosed a small head gasket leak in a forum members SDL.

I also used it to rule out problems on my 85.

It works well - easy to use and it's super sensitive.

dd

BimmerBenz · #7 02-13-2011, 03:03 AM

If you have a clutch fan that is your culprit. If you do have a clutch fan let me know and I can give instruction on how to test it. Basically the fan should only move 45 degrees or 1/4 turn if you check immediately after shutting off a hot engine. This is not 100% though.
If you do have a clutch fan I can tell you with 90% certainty the clutch has failed and replacement will solve your issue.

If the fan spins relatively freely by hand when the engine is cold you have a clutch fan. If the fan blades do not move when you try to spin it you have direct drive.

If you have a direct drive fan have you removed the rad/fan shroud?

EDIT: Reading is apparently not my strong suit.
I see you have a clutch.
Heat the engine to operating temperature. As the temperature gauge moves across 1/2 on the gauge listen closely to the fan. It should make a very distinctive transition to engaging and blowing air. If your temperature gets to 60% gently force a rolled up newspaper into the fan blades. You should NOT be able to stop the fan; it should shred the newspapers. If you can stop the fan the clutch is bad.
Clutches MUST be stored in a warm environment in the nut down position for at LEAST 24 hours before installing.

To test head gasket:
Cold engine, open hood.
Start engine then grasp the upper rad hose. It should be 'squishy'. Keep squeezing it. It should remain soft for 10 minutes of testing and actually at least until the operating temperature hits 50% on the gauge. If the hose gets hard in under 10 minutes you have a HG issue.
Open the expansion tank/overflow bottle. Fill it to the top with coolant. Start the engine. There should be no bubbles and no odour of diesel fumes.
There should be no white 'cream' or residue on the oil cap or on the dipstick.

vstech · #8 02-13-2011, 10:32 AM

he stated he "traded out his fan clutch" does this mean a NEW clutch was installed, or just another used one from a different car?

cousindave76 · #9 02-13-2011, 01:21 PM

Quote:

Originally Posted by RAYMOND485

1984 300D 156K TURBO
replace the radiator and refill with car front up diy.also r&r two radiator hoses

I replaced the radiator with a new BEHR 4 years ago. I've flushed and maintained ever since. Could that really be the problem?

cousindave76 · #10 02-13-2011, 01:24 PM

Quote:

Originally Posted by GregMN

If you run the defroster, does the temp go down? if so, check your radiator.

I found running it will drop my temps bout 5 Celsius. If I sit in traffic too long, the engine will continue to overheat until I have no choice but to pull off and shut down.

cousindave76 · #11 02-13-2011, 01:27 PM

Quote:

Originally Posted by vstech

I've got one that does this. normal but for 120C peaks on occasion. I drilled a hole in the tstat and the temps stay rock solid at 80ish again.

I've read about drilling holes in the t-stat. I never tried it. What the heck, it's free and easy to do. I will do this and see if it helps.

cousindave76 · #12 02-13-2011, 01:33 PM

Quote:

Originally Posted by charmalu

Discovered the ground strap from the engine to body wasn`t making a good connection. removed it, cleaned up the contact areas, and all has been well.
Charlie

I really wish this was my problem. However in my case, when I shot the block with the infrared I found the engine temps are in fact as high as my dash temp gauge is telling me

My dash temp gauge is reading only about 1.5 Celsius higher than the the reading I get from the infrared.

cousindave76 · #13 02-13-2011, 01:35 PM

Quote:

Originally Posted by dieseldan44

Dave, I have used this block test kit:

http://www.amazon.com/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76/ref=sr_1_11?ie=UTF8&qid=1297583029&sr=8-11

I successfully diagnosed a small head gasket leak in a forum members SDL.

dd

That's just what I wanted to know! Thank Dieseldan44! Looks like I'll be needing to perform this test.

GregMN · #14 02-13-2011, 01:37 PM

If it only overheats when sitting and does not overheat when moving down the highway, then you have an air flow issue.

Check your fan clutch operation.
Check for debris blocking your radiator.

cousindave76 · #15 02-13-2011, 01:45 PM

Quote:

Originally Posted by BimmerBenz

If you have a clutch fan that is your culprit.

To test head gasket:
Cold engine, open hood.
Start engine then grasp the upper rad hose. It should be 'squishy'. Keep squeezing it. It should remain soft for 10 minutes of testing and actually at least until the operating temperature hits 50% on the gauge. If the hose gets hard in under 10 minutes you have a HG issue.

Good info on the fan clutch. I do think mine is not in the best of shape. I did not replace with a new one, I got a used one. They seemed to operate the same. I did try this. Since I have two of them, I locked down one of them and installed it. I found that with a direct drive fan my temps lowered to just below red-line while sitting in traffic. This solved my problem of being able to get around however, my fuel mileage suffered and the fan was very loud at speed. So I switched back to the other fan and am now once again hunting down whatever is making the engine way to hot in the first place. Correct me if I'm wrong, but would a direct drive fan overheat my engine while idling in traffic? If not, I have other issues than a fan clutch.