Ok, seriously, help?
Thread Starter
Newbie
Joined: Mar 2010
Posts: 10
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From: Reno, NV
'78 300D, more to come soon!
Ok, seriously, help?
Hi guys, I posted this in tech talk about a week ago and didn't get a reply:
To update, I replaced the water pump this morning. Everything seemed fine except my fan/pump/alternator belt was really loose. When everything was done I took her out for a spin, and the temp rose slowly to normal, hung there for a couple minutes, then began to rise right back up, almost to where it was before. The problem seems slightly better, and the leak is gone, but why is it still running hot?! This is driving me crazy! Please help!
Recently I took my 78 300D on a short road trip, about 110 miles to go camping with some friends. On the return trip, about the last 30 miles, i noticed the temperature had risen to about 190-200F, not red lined, but hotter than normal. A quick visual check showed no obvious problems, good fluid levels, and no leaks, smoke, or bad smells. I initially suspected the thermostat, drilled a few small holes and saw a slight improvement, so i replaced it all together right before embarking on a much longer road trip (about 350 miles). It made the trip fine, but still ran hot, around the same temperatures as before. Near the end of the trip there, i noticed a slight hesitation at freeway speeds, it seemed random, and only noticable above 60, almost like some additional parasitic drag on the engine. There were no strange noises or other engine problems. The next morning I noticed a small puddle of coolant under the oil pan, but it only looked like it had been dripping for an hour or so, and it appeared at first to be coming from behind the crank pulley, but closer inspection revealed (at least I think) that it was coming from the water pump. Also, the leak stopped the moment I started the engine. There is no coolant in the oil or vice-versa, and I don't believe it's an internal engine problem, although... ?? Anyway, I'm set to replace a water pump, but thought I'd ask before I waste time and money fixing something that isn't the problem.
Banned
Joined: Sep 2009
Posts: 48
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From: So CA
1984 300D,82 Volvo Diesel
Hi guys, I posted this in tech talk about a week ago and didn't get a reply:
To update, I replaced the water pump this morning. Everything seemed fine except my fan/pump/alternator belt was really loose. When everything was done I took her out for a spin, and the temp rose slowly to normal, hung there for a couple minutes, then began to rise right back up, almost to where it was before. The problem seems slightly better, and the leak is gone, but why is it still running hot?! This is driving me crazy! Please help!
To update, I replaced the water pump this morning. Everything seemed fine except my fan/pump/alternator belt was really loose. When everything was done I took her out for a spin, and the temp rose slowly to normal, hung there for a couple minutes, then began to rise right back up, almost to where it was before. The problem seems slightly better, and the leak is gone, but why is it still running hot?! This is driving me crazy! Please help!
Could be the Raidator is becomming restricted either inside or maybe the exterior fins have become full of dirt blocking the Air from going throuh the Radiator.
My last though is that you could have a small Head Gasket leak that is causing gas pockets inside of the Cylinder Head. This would cause local overheating.
You could also consult a regular Motors or Chilton type manual for the normal problems that would happen on any cars Coolant system.
If you have an Auto Trans besure there is enogh Fluid in that as the Trasns Oil is cooled in the Radiator; if it is too hot the Radiator has to try to get rid of that heat also.
Thread Starter
Newbie
Joined: Mar 2010
Posts: 10
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From: Reno, NV
'78 300D, more to come soon!
I do not know if your year of car has the Viscous Fan or not but if there is a problem with that your Fan may not be turning when it is supposed to.
Could be the Raidator is becomming restricted either inside or maybe the exterior fins have become full of dirt blocking the Air from going throuh the Radiator.
My last though is that you could have a small Head Gasket leak that is causing gas pockets inside of the Cylinder Head. This would cause local overheating.
You could also consult a regular Motors or Chilton type manual for the normal problems that would happen on any cars Coolant system.
If you have an Auto Trans besure there is enogh Fluid in that as the Trasns Oil is cooled in the Radiator; if it is too hot the Radiator has to try to get rid of that heat also.
Could be the Raidator is becomming restricted either inside or maybe the exterior fins have become full of dirt blocking the Air from going throuh the Radiator.
My last though is that you could have a small Head Gasket leak that is causing gas pockets inside of the Cylinder Head. This would cause local overheating.
You could also consult a regular Motors or Chilton type manual for the normal problems that would happen on any cars Coolant system.
If you have an Auto Trans besure there is enogh Fluid in that as the Trasns Oil is cooled in the Radiator; if it is too hot the Radiator has to try to get rid of that heat also.
Senior Member
Joined: Sep 2009
Posts: 361
Likes: 3
From: Chicagoland
2008 ML350 4matic
I am thinking fan/fan clutch....any leak in the head gasket should result in oil in the coolant, coolant in the oil, or coolant in the cylinder. Coolant in the cylinder would/should burn white smoke with a very distinct "sweet" smell. You have neither of the other two....plus, with a new water pump and newer radiator....fan/fan clutch seem the next logical.
Senior Member
Joined: Sep 2009
Posts: 361
Likes: 3
From: Chicagoland
2008 ML350 4matic
My experience with fan clutches has only been with American cars, but here it is....
A good fan clutch will have a heavier resistance when trying to turn it by hand and a bad or going bad clutch will be easier if not free spinning by hand.
Please dont take this verbatim, but it was the trick with Chevy, Dodge and Jeeps....
It's a fairly cheap part compared to a head gasket, plus, you're pretty much ruled that out anyway.
I will consult a Ford Master Tech on the 12th to confirm the clutch wear idea....
A good fan clutch will have a heavier resistance when trying to turn it by hand and a bad or going bad clutch will be easier if not free spinning by hand.
Please dont take this verbatim, but it was the trick with Chevy, Dodge and Jeeps....
It's a fairly cheap part compared to a head gasket, plus, you're pretty much ruled that out anyway.
I will consult a Ford Master Tech on the 12th to confirm the clutch wear idea....
Senior Member
Joined: Sep 2009
Posts: 361
Likes: 3
From: Chicagoland
2008 ML350 4matic
OK....spoke to a M/B tech today who confirmed the fan clutch theory, brought mine in to have the summer tires put back on.
If it is bad or going bad, it will spin with little resistance. If it is really bad, it may have leaked an oily substance out near the spring....He also said if the car starts running hotter than usual with no other issues( radiator, water pump, old coolant) it will more than likely be the fan clutch.
If it is bad or going bad, it will spin with little resistance. If it is really bad, it may have leaked an oily substance out near the spring....He also said if the car starts running hotter than usual with no other issues( radiator, water pump, old coolant) it will more than likely be the fan clutch.
