Head Gasket Replacement

[s class]

Well I'm glad to hear you are keeping the car!

A leak that bad is unlikely to come from the head gasket unless accompanied by other serious symptoms. 

[brettj]

I agree.  I've heard of a dye test to determine the source of oil leaks. Is there a kit you buy with the dye? Do you just dump the dye into the crankcase?

[koan]

I've used "Tracerline" dyes, comes is small bottles, available in car part outlets (Repco amd Burson in AUS).

You'll also need a UV compact florescent lamp to see the dye.

Have to be careful with big leaks, put the dye in then run the engine for 5 mins and have a look, repeat until the leak is found. First time I used it I drove around for the day which spread the leaking oil everywhere, defeating the purpose.

koan

[brettj]

This leaking stuff is going crazy! I drove the car 40 miles today. The motor did not leak all day. I parked the car  around 3pm today, went out again in my other car and returned home at 7:30pm only to find another large oil puddle under the rear of the car by the rear drivers side wheel. I looked under the car and noticed oil drips on the exhaust pipes. Could the motor be sucking oil through the exhaust pipe? Is that even possible? Or is it a sign of bad head gaskets? The rear end has not leaked in well over a year since I changed the axle seals but the oil on the ground is definitely a yellowish color suggesting motor oil. Is the axle oil yellowish in color too? If I remember right the axle oil is more of a reddish color like transmission oil.

[Papalangi]

Pull the dip stick, drop some oil on a paper towel.  Dip a towel in the puddle and compare the two.

It is possible to pump oil out the tail pipe but the last time I did it, it was with a 1972 Renault 12 wagon.  I just towed it to the junk yard.  I'm hoping that your problem isn't quite so drastic.  It could be that the crankcase breather has plugged up and the back pressure is pushing oil out the dip stick or some other weak point.

I used a dye kit from JC Whitney but didn't have much luck.  I still don't know where all it's leaking from.

Michael

[s class]

The original axle lubricant is a red colour.  If they have been serviced in recent years, they would probably have been refilled with a high-load hypoid oil which is yellow in colour.  But as papalangi suggests, do the paper towel comparison to determine if it is indeed engine oil or not. 

If the leak is at the left rear wheel, I would suspect a hydro oil leak.  Does your car have SLS (self levelling suspension)?  THe fluid for this system is thin, and yellowish.  THe SLS stuts can leak, and the flex hoses to the struts can also deteriorate and leak. 

[Papalangi]

I think s class is onto something.  With the engne running, there is enough pressure to hold a seal tight but as the system bleeds down, it can begin to leak, especially it the strut rod is damaged where it passes through the seal.

Michael

[brettj]

Morning,

I left the car in the garage last night. Pulled it out this morning to check for leaks. The only leak that was found was a very small leak at the rear of the motor. This oil leak is about an inch in diameter. There were absolutely no leaks from the rear end.

My car does not have SLS. I did change the axle fluid last year.  I guess the leak that came from the rear end could be from the axle. I drove the car to work today to see if it leaks more today.

Oscar, for the life of me, I can't find the oil line you described. Maybe it wasn't in the design of the 1975 450SE?

[Papalangi]

Brett,
Humor me and check that the master cylinder is still full.

Michael

[brettj]

I checked the master cylinder fluid level. It was full but the color of the fluid looked the same as what had leaked under the rear of the car. So perhaps it was brake fluid. I drove the car 65 miles yesterday both in the city and on the highway. I looked under the car this morning and found no leaks! Do leaks start when a car sits for a long period of time? I don't drive my car much in the winter months.

Also, yesterday the warm start stall issue returned again after driving the car a lot with lots of starts and shut offs. There is one part that I never thought of that may be the cause, the electronic switching unit. After I let the car cool down, I moved the green distributor wire from side to side at the connection with the electronic switching unit. I then drove the car another 20 miles with lots of shut offs and starts. The warm start stall did not occur at all. Perhaps it has been the switching unit causing the warm stall probelm in the first place. Does that make sense?

Oscar, I finally found the oil pressure line you were talking about. It is totally different from the set up in your car. All my car has is a long rubber hose that feeds  directly into the firewall and out to the oil cooler. The hose is attached to the power steering hose. It doesn't appear to be leaking.

[Papalangi]

I checked the master cylinder fluid level. It was full but the color of the fluid looked the same as what had leaked under the rear of the car. So perhaps it was brake fluid. I drove the car 65 miles yesterday both in the city and on the highway. I looked under the car this morning and found no leaks! Do leaks start when a car sits for a long period of time? I don't drive my car much in the winter months.

It's good that the master cylinder is still full but odd that it's the same color as the brake fluid.  Next time you see that color fluid on the ground, feel it between your fingers.  Oil will be slippery but brake fluid will have that slippery but not feel that only it has.

It is entirely possible for fluids to be carried down the length of the car by air flow, collect somewhere and then drip after the car has come to a stop.

I lost the left rear shock this winter after the third or fourth day of mid 20's (F) temperatures.  It left a puddle about 5" round directly under a CV joint.  It probably would have been amber colored originally but was a rather nasty black by the time it hit the ground.

Michael

[oscar]

Oscar, I finally found the oil pressure line you were talking about. It is totally different from the set up in your car. All my car has is a long rubber hose that feeds  directly into the firewall and out to the oil cooler. The hose is attached to the power steering hose. It doesn't appear to be leaking.

Sorry I couldn't get back to you sooner I was away, but I didn't expect to hear that line was in a completely different place.  No oil cooler on mine.  By the sounds of it another dead lead too unfortunately.  Haven't got any solutions though I still don't buy the "needs a head gasket" claim when your engine isn't showing signs of a cactus gasket.

Any luck on locating the source of the rear of the car leak?  I had a caliper leak in the 280 that didn't show as a drop in the brake fluid reservoir.  It must have dropped but I didn't notice.  I only found the leak after it had coated a rotor and seeped inside the rim, down the tyre and onto the floor.  I wasn't driving the car much and only noticed the leak once, though it's likely it had been there for a little while. 

[brettj]

Hi Oscar,

The car never leaked again in the rear end area. The engine leak also has changed location. Now the oil spots are located at the middle section of the motor. The original spot at the rear has gotten smaller and or has not been leaking like it was last week. I'm at a loss  as to where the leaks are coming from.

The hot start stall issue is back. I've been playing with the electronic ignition unit.  I think that's the cause of the problem. I picked up a used ignition unit on EBay. I'll switch the units to see what happens.

[Papalangi]

I like to think I'm known for off the wall observations at times.  Here is another one.  Could it be that the last time someone added oil, they spilled a bunch where it didn't go or even left a bottle somewhere in the engine compartment and it took awhile to drain out?

Michael

[brettj]

No, I wish that were the case. I drove the car today and it started leaking again. I'm going to take the car to another mechanic to get a second opinion on this issue. I'm afraid that it may come down to head gasket replacement.