Did my mechanic mess up this block heater installation?
 

Hi Folks,

Did my mechanic mess up my block heater installation? I purchased a 1000-watt tank-type block heater from JC Whitney for about $35. My mechanic said he could install that for $50, and probably $200 for the standard MBZ block heater, since it's harder to install. I opted for the JW Whitney one.

For anyone who doesn't know, the tank type block heater is a metal cylindrical tank about 4 inches in diameter and about 10 inches high, with a coolant in port on the bottom side and a coolant out port on the top. It has a built in thermostat and the manufacturer claims that in about 2 hours, the coolant in the system should be about 140F/60C. It works via the thermosiphoning principle, in that it heats the coolant, which then rises through the block and then as it cools descends through the circuit to be sucked into the block heater again.

Anyway, here's a picture of their installation. They charged me $115, more than twice what they said it would cost, because they found it very hard to do. It seems like they didn't follow the instructions that came with it at all. They mounted it VERY high in the engine compartment, and the out port leads to a high loop. The mechanic warned me that the loop was so high that if coolant in the radiator expansion tank dipped below the level of the loop "you could start a fire."

The instructions specifically say not to have any loop above the heater where hot coolant could collect.

When I plugged it in and left it for 3 hours, the temperature of the block was only 10 deg F above ambient (80F, ambient 70F). The temp gauge on the dash, when I put the car in Run, read nothing. The loop right above the block heater was 120F, but 3 inches down towards the engine on that hose, it was cool. Also, the hose attached to the bottom was hot, which the instructions warn is a sign of it not being configured correctly.

Shouldn't my block get hotter? Should I take it back to them? Should I ask them to fix it? Any chance they'll fix it for free? Should I just forget using this kind of block heater and have them install the OEM one?

Here's a picture of the installation. The block heater is the silver cylinder in front of the expansion tank.

Thanks!

I'm wary of any claim by JCWhitney, and I haven't bought anything from them in years. The fact that the coolant heater connects to the heater loop limits it's effectivity because of the small hoses restricting the passive circulation. I would give it a chance if it connected directly to the lower radiator hose, otherwise I doubt that heater would be very effective.

On the other hand, your mechanic is at least partly right that the factory block heater is a PITA to install, especially with the engine in the car. But it works.

It appears that it was installed in the hose to the expansion tank! If so, that simply won't do, as the coolant doesn't normally flow thru that line.
The temp gauge not showing heat is proof it isn't working properly.
Better tell them it isn't going to work, and hopefully they will change it at their expense! I think they should have installed a block heater for that price!

I have bought 2 new Benz block heaters and never paid more than $34 for one and $45 for the other....

From the dealer I doubt they top $75.

i believe
 

my indy charged me one hour to install. it is not easy but not complicated. just takes a long breaker bar and must be done from under the car.

tom w

Did you turn the heater controlls inside the car to full heat when you turned the heater on? The heater controll valves MUST be fully open, or else they will block any effective circulation.

You can check if they installed it in the right place by following the heater hoses. The heater should be installed in the heater return hose from the firewall to the waterpump. On my W115, this hose runs along the passengers side of the engine. There might be an arrow on the side of the heater as well. This should probably point towards the water pump (where the hose connects with the engine).

Looks to me like your tech did the job as he was supposed to do. However, he cannot be responsible for the item not working the way it was supposed to do either. This is assuming the instructions told him where to install it.

Every mechanic I called (main, well established one, and the smaller cheaper one) quoted me at least 2.5 to 3 hours of labor to install. They said they wouldn't use a breaker bar. They said they would have to remove the starter and a bunch of other stuff to get to it. That sounds like bull, given what EVERYONE here has said about just crankin' on it.

As for the earlier post about connecting to the expansion tank, it's definitely not connected to the expansion tank.

I have tried setting the heater to its max setting immediately, but it doesn't help. It still takes just as long to warm up.

Do you guys see what I'm talking about re: thermodynamics? Maybe I'm wrong, since this is a closed loop kind of system, but with the heater near the highest part of the coolant jacket, and having a loop over it, I think heated coolant is just "hanging out" in the hoses right next to the heater. The heater also cycles really fast, since the heat just builds up right next to it. I can hear it turn on and then off really quickly.

How hot should my engine be with a decent block heater?

This is really irritating.

They did! The instructions have diagrams showing you NOT to do exactly what he DID do. Big pictures with an OK next to mounting it low, big X's over mounting it high and with any loop over it.

This is what I get for trying to save a few bucks by going to a cheaper mechanic.

you seem to be knowledgable about your car and the system you wanted to install...
why didn't you just install it yourself?
this way you would've saved the most bux

I agree, but I am sure he has his reasons. Just because you have the knowledge doesn't mean you have the time. (being a student I lack both most of the time!)

Anyways, do you still have the instructions? See if there is some sort of mark on the heater saying which side is supposed to go where, and if maybe the mechanic put it in backwards. Next, see if you can re-arrange the hose that is already in there to eliminate the loop, because I do agree that it would seem to cause a problem (especially since the instructions say not to)
If that doesn't solve it, I would head back and tell them to install it right, or head to DIY.

I have the time, but not the desire to have to store/dispose/replace all the coolant and hack into heater hoses. Futzing with the fuel system is enough for me right now.

I have the instructions. It's pointed up correctly, but it is wrong in every other way according to the instructions.

So does anyone here have a block heater? What does your engine temp read after leaving it on for 3 hours?

The proper in-block heater will get the coolant and the block to 40-45C in 3 hours, even at 0F outside. It's a darn shame what that guy did. If he had more sense and pride he would have declined to do it any other way than in the block, which IMHO is the only correct way. As for removing the original plug without a breaker bar, you did not speak to anyone who has actually done it.

Your heater won't thermosyphon beceause the tank heater is mounted too high. The cold water should fall into the heater, get heated, then rise out of the heater. Mine was mounted on the wheel well - passenger side, battery is left front on my model - water fell out of the second-from-the-rear frost plug then rose into the return line for the heater core.

Where are your tank heater hoses connected? I may have an idea.

It looks like the bottom intake on the tank heater got teed into the output of the water pump, or whatever is a 5/8" hose right above the alternator.

The output loops and disappears under the passenger side of the engine. I have no idea where it goes. I couldn't see from the top or looking up as best I could from the bottom.

Is it at all a good sign that the top radiator hose gets close to 85F? Seems not nearly hot enough, though.