Greasecar Installed & Only 110F...Need Heat! - PeachParts Mercedes-Benz Forum

diesel don · #1 08-22-2009, 10:38 AM

From searching the forum, I note that many of you opted to ADD a FPHE (Flat Plate Heat Exchanger) to bump your heat up. I have a few questions relative to additional heat (1984 300DT):

1. In adding a FPHE, where did you T to get coolant (from the hottest part on the engine side?)
2. Where did you add the fuel lines?

3. I currently have the long return coolant hose (from the veggie tank in the trunk) T'd in after the monovalve. Does that compromise heat? Has anyone moved it over to the engine side of things or does that mess with the circulation?

4. It would figure that of all my MB's, this one runs the coolest, with temps barely exceeding 80C on an 80F day at full load. Is there a way to change this by adding a higher tolerance thermostat or diluting with more water (perhaps my concentration of coolant is too high)

5. Would a non-functioning monovalve mess with the heat?

Thanks in advance for any help on the matter.

Diesel Don

first300D · #2 08-22-2009, 11:33 AM

Hi,

I have mine T-ed (start flow) from right near the Oil Filter and the heater hose that comes out of the Block.

Then the Return is over tope of the Alternator where the heater Hose is going back to the Block/Water pump.

Also it sounds like you may need to inspect/replace your Thermostat. It really doesn't sound like your 300 is getting to good operating temperature which in it self will not allow your diesel to run optiumally.

diesel don · #3 08-22-2009, 11:58 AM

Thanks!

It sounds like our coolant hoses are in the same place. I'll keep an eye on the thermostat, but it is allowing the car to achieve about 85-90C before opening. Cool

thanks again

dd

pselaphid · #4 08-22-2009, 03:33 PM

Regarding your monovalve questions, you might not compromise heat function with the downstream splice, but you will compromise AC function. The monovalve will not close properly with the excessive pressure of the heat return line downstream, which I think is where you are describing your splice. Somewhere on this forum is a thread about replacing the monovalve with a 70s vintage Ford vacuum valve, activated by a vacuum relay (actually an overboost switch or relay) energized by the monovalve circuit. Really its quite simple to retrofit. The problem can also be dealt with by installing a summer/winter shutoff upstream from the monovalve, but the retrofit is a better, no maintenence, solution and works great. You're in Michigan, so AC might not be an issue, but it is in Louisiana! And I concur with checking or just replacing the T-stat. That might solve the problem right there.

Mine is plumbed as described above, t-d out of head, then FPLE, then heated filter, then around back of engine bay t-d downstream from Mono, as seen in this photoset: http://www.flickr.com/photos/12666884@N00/sets/72157621660693605/

diesel don · #5 08-22-2009, 04:37 PM

That's really starting to make sense, with the downstream Monovalve pressure. What's even more complicating is that prior to the install, I knew my monovalve was shot cuz the AC was blowing only hot. I therefore threw another in and the second one is acting funky. Makes sense now

thanks a bunch

dd

marybeth · #6 08-22-2009, 07:12 PM

pselaphid is correct in his flow diagram of coolant heat.

You wish hottest coolant coming out of the engine head to be into the FPHE. The FPHE is the last place the WVO will come into contact with coolant-so you wish the FPHE coolant to be at max temp.

Make sure the coolant and WVO are plumbed to flow in OPPOSITE directions. When WVO and coolant flow in opposite directions heat is exchanged.

Also having the AUX pump or adding an AUX pump to help 'pull" the coolnat thru your WVO will increase warm up time of the WVO.

Here is good thread
http://www.frybrid.com/forum/showthread.php?t=8689

pizzachef · #7 08-22-2009, 08:10 PM

Looks like you've got good advice so far. Where are you measuring your fuel temp? It should be between the lift pump and the IP to get the best measurement for the temperature of the fuel being injected.

I'm not exactly sure where you have your coolant tapped, but here's what I would advise...you may already have yours set up like this. Put a T in the coolant line where the coolant exits the head and goes into the firewall (to the heater core). The coolant from there goes right into your FPHE, then the heated filter (if you have one), then the heated fuel lines, then the tank, then to another T in the line near the aux pump behind the passenger-side headlight (you can put it just upstream of the pump and wire the pump to have key-on power to help you have better flow...I have no aux pump and get good fuel temps and good heat in winter at idle).

A faulty monovalve shouldn't affect your VO temps much at all, your VO loop should be in parallel to the heater circuit. If its stuck closed, all the coolant will flow through the VO loop, no prob...if its stuck open, it'll act just like the heater is on and will take a little longer for the fuel temp to increase, but it'll eventually get there. Mine works fine in the winter with the heater blowing.

Diesel Dan · #8 08-22-2009, 11:37 PM

You might also try insulating your WVO tank and hoses. Every little bit helps!

diesel don · #9 08-23-2009, 07:54 AM

Pizzachef:

Thanks a bunch as 'light bulbs' are coming on in my mind.

1. I'm measuring the temp of the VO at the output (brass) on the top of the heated fuel filter, but I suspect it's not accurate. Drove ten miles home last night and VO temp never registered above 85F (strange as it was 120 earlier in the day). Also, temp falls as I drive and rises as I'm stationary

2. Right now my 'T' on return coolant is 3" below monovalve. If I move it close to Aux pump and wire that pump to 'on' with key switch, will that solve the pressure issue that the monovalve has with the AC function (see previous poster's concern)

3. What type of temp device do you use between lift pump and IP?

4. I'm going to insert a FPHE at the earliest exit point of hot coolant from the engine (first in line for coolant, last in line for injected VO right?)

thanks again for all the help

dd

pselaphid · #10 08-23-2009, 09:27 AM

Some of the WVO vendors have started selling the aux fuel pumps to be wired to run continually for quicker heatup, so it might be worth experimenting with. This might relieve the pressure enough for nomal monovalve function. Be sure to install an inline fuse (do a search for correct amps, but 1 or 2 amp as I recall) as a precaution. And report back.

diesel don · #11 08-23-2009, 09:35 AM

Good idea on the fuse. Will add that to the list. It'd make sense that the additional flow would relieve some pressure from the monovalve, but this is from my 'rookie' mind. Didn't know what a FPHE was until two days ago.

Fun little project

dd

first300D · #12 08-23-2009, 11:35 AM

Quote:

Originally Posted by diesel don

Pizzachef:

Thanks a bunch as 'light bulbs' are coming on in my mind.

1. I'm measuring the temp of the VO at the output (brass) on the top of the heated fuel filter, but I suspect it's not accurate. Drove ten miles home last night and VO temp never registered above 85F (strange as it was 120 earlier in the day). Also, temp falls as I drive and rises as I'm stationary

2. Right now my 'T' on return coolant is 3" below monovalve. If I move it close to Aux pump and wire that pump to 'on' with key switch, will that solve the pressure issue that the monovalve has with the AC function (see previous poster's concern)

3. What type of temp device do you use between lift pump and IP?

4. I'm going to insert a FPHE at the earliest exit point of hot coolant from the engine (first in line for coolant, last in line for injected VO right?)

thanks again for all the help

dd

Call me slow. But you mentioned to me earlier that you thought your was T-ed like mine. From what your saying above it sounds like you have your return T-ed between the monovalue and the aux pump?? Am I hearing this correctly ?

If that is true for you then it is in deed not as mine is. My Return T is between the Aux pump and the Engine Block over the Alternator.

Let me know.

pselaphid · #13 08-23-2009, 12:50 PM

You are correct, you have your's on the other side of the aux pump. That may be a better location for monovalve function. I put mine on the back because it allows the hose to be routed more conveniently.

diesel don · #14 08-23-2009, 10:38 PM

Yep, I missed your location. That seems even better (between aux pump and engine, over the alt). It's starting to make more and more sense in my brain (takes awhile to get it).

I'm going to do two adjustments: 1) add a FPHE and 2) change the location of the second T (along with wiring the aux pump for continuous action)

Thanks for the patience

dd

first300D · #15 08-24-2009, 02:45 AM

Ok in addition to my T locations.

I have a FPHE
I have a home made HIH(Hose In Hose) 6 foot long.

My system is not a greasecar system but is a two tank setup. I just don't heat my WVO Tank.

Once the Car is to operating temp My Oil Temps once flowing will hit 150 + relatively easy. My HIH uses aluminum pipe. Does Grease Car still use PEX tubing ?
BTW My WVO Temp sender is just before entry into the lift pump.

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