And yet another Toyota swap, but M-Tdi.

OK, confusion time. I've been working on the cooling system, I've got the upper and lower radiator hoses hooked up but I can not wrap my head around the fact that all the diagrams show the return from the radiator going in the bottom of the water pump (WP) through the thermostat. I would think that as soon as the thermostat opened and the water started flowing from the cool/cold radiator the thermostat would immediately close again before the engine had a chance to cool down.

Does the coolant in fact flow out of the head to the radiator and back in the bottom of the WP through the thermostat? And if so how the hell does this work? I know that I have read several places in this forum that this is how it flows but it don't make no kinda sense.

Second question. The heater core is supplied hot water from the back of the head and is returned to the WP near the thermostat, as per the various diagrams I have found. I remember reading somewhere that you do not want to block the outlet from the back of the head, but in Toyotas the heater system has a valve to throttle the hot coolant flow through the heater core and when the heat is turned off the flow to the heater core is effectively blocked off and therefore the flow out of the head is also blocked off. Has this been a problem for anyone that has done this Toyota swap? Does there need to be some sort of bypass made here to allow coolant flow when the heater core valve is shut off?

This whole cooling system seems to be ass backwards to me, what with the thermostat being at the bottom "inlet" of the motor.

Thanx for any advice here,
Jaysin

you got it right ....t-stat goes to lower rad hose....as for blocking the coolant flow the back of the head I guess the AHU/1Z is a bit different...on the ALH the coolant flange @ the rear of the head flows to the upper rad and also flows to the heater core so blocking that flow via the toyota heater valve is not a problem....someone else may want to chime in on how you should do this....maybe you can "T" into the upper rad hose for your heater?...this way if you turn off the valve it won't affect flow from the rear of the head... as for seeming backward I know some of the toyota V6 engines placed the t stat @ the lower hose....It's confusing to me too but it seems to work ....EDIT!!...actually now I'm really confused...because the upper rad hose on the AHU is @ the front of the head...so where does the coolant flange @ the end of the head go?

Well see, Im not the only one who's confused. The upper radiator hose isn't really at the front of the head it's about 3/4 the way to the rear. The coolant flange at the rear of the head goes to the heater core/egr cooler and returns to the water pump. The way it seems to me is that if coolant is blocked out of the rear port to the heater core then the coolant should al flow around in a circle from the engine out to the water pump back in, either through the radiator or (when the t-stat is closed) through the bypass hose. But I remember reading somewhere that the rear heater core port shouldn't be blocked. Could someone with a ahu/1z shed some light on this?



And I really still don't understand how the T-stat can be in the return/cold flow. So if anyone can shed light on this too I would be grateful. Or are the flow diagrams wrong and the water actually flows out at the bottom/water pump (reverse flow)?

Thanx,
Jaysin

You could t the oil cooler into the heater hose after the rear flange and before the yota valve this way you have a constant loop .... As for the flow I'm not confused on the direction it does flow cool h2o from the lower rad through t stat .... Alh on my truck works the same way and works great

Jimmy,

I'm sure it works or the cars would all overheat. I just can't figure out how it works, I don't know how the T-stat would stay open when cool radiator water flows through the moment it opens. I want to make sure I don't screw up any part of the circuit and make it not work. Thanx for verifying the flow direction for me.

Thanx,
Jaysin

So I have been working on the injector pump and swapping parts and pieces back and forth between pumps. What I will end up with is a 12mm head with Tdi cam plate in a cummins 4bt pump body. Well this got me thinking about nozzles. I have been told that I should use at least .216 injector nozzles but I was wondering what people that are following my build think? With the BV43 turbo and 12mm head should I go bigger? I have been looking at one of the vendors selling HFLOX nozzles and along with .216s they have .230, .240, .250, etc... They seem a bit cheaper then Bosio and the like but seem to have good things said about them. Mostly I would just like to hear some input about nozzle size.

Thanx,
Jaysin

On my truck I'm running pp502 with 12mm head and pd130 turbo (1749va) it's a good combo (very torquey) although I could prob get away with 11mm fine as the fueling in is cut way back via tune right now

1Z TDI Cooling System

Where is the expansion tank in the above diagram? Off hose #10 and #2?

Now I am wondering about the system as well. I'm re-posting this email as I understand the 1Z cooling system and as it's built on my truck. Possibly wrong. Wisdom welcome. In this text, I am answering questions (they're in quotes) and referring only to my truck.
This made sense to me because the idea is to cool off the coolant after it leaves the block. The heater core does this - or barely does, depending on where the driver has the heat switch set. That hot coolant then goes to the water pump and to the radiator, its primary source of shedding heat and cooling off. Then the cooled coolant is pumped to the head again. Some of that cooled coolant drops to the oil cooler at that three-way where the upper radiator hose goes in to the head.
http://forums.tdiclub.com/showpost.php?p=3375030&postcount=97
and in subsequent posts, on the coolant flow arrangement. Both e*clipse and I thought, 'oh s#@!.' (e*clipse's Toyota is worth seeing if you haven't. e*clipse changed his plumbing. I have not. I live in such a cool climate, and when monitoring temp with the laptop/VAGCOM, it has always stayed within limits, even when charging up to Donner Summit from Sac. I actually have the coolant temp gauge, and it will go in.... sometime this winter I need to change out the old rusty radiator (it's original - going to get an alum. one).

What I think Goldguru is suggesting is that I'll get hot spots in the motor the way I have the coolant system routed and I'll blow a head gasket. But I honestly don't completely understand his convoluted, unpunctuated, randomly capitalized post - sorry. I want to. It is a way of looking at things I think I need to better understand. I also probably don't understand the thermostat well enough. But my cooling system works...

cumminsfromthecold said:

What I think Goldguru is suggesting is that I'll get hot spots in the motor the way I have the coolant system routed and I'll blow a head gasket. But I honestly don't completely understand his convoluted, unpunctuated, randomly capitalized post - sorry. I want to. It is a way of looking at things I think I need to better understand. I also probably don't understand the thermostat well enough. But my cooling system works...

Click to expand...

I agree that Goldguru's post is hard to parse. However I think he may be on to something.

Consider that the heater setup on my conversion is an extreme version of yours (and stock). I have 10 feet of hose running from the rear of the bus up to the the heater core up front, then 10 feet of hose running back. That's a fair bit of cooling.

My observation is that this delays the thermostat in opening.

I had a run a week ago where the heater fan was on and I was seeing the water get up to 200* on the Scangauge. It occurred to me that the water was getting cooled too much by the heater circuit. I didn't want to continue the experiment so I shut off the fan and the water temp returned to normal.

I will repeat the experiment and see if it's consistent. If so, plumbing the heater into somewhere else (after the oil cooler?) might make sense.

What do you think?

Mark

As far as my ahu is concerned, I have the port from back of the head flowing through EGR cooler then directly to heater core. Since the toyota heater core shuts when you slide it to cold, I tee'd right before the valve to divert the flow back towards the water pump (yellow line on your diagram) when shut. I can throw up some pics if you want.

As far as I know the goal is to apply heat directly to the top of the thermostat at all times.

The point is do not stop the flow from the back of the head or you will eventually overheat the engine. Good luck!

Check out a caterra heater valve it's a three port it may divert but it's vac controlled

Wow, thanx guys. This is great information (albeit still a little confusing).

Cumminsfromthecold, you seem to be saying that the system is reverse flow, hot out the bottom cold in the top, is this what you have found?

But I really like the idea of a bypass line like ToyotaTDI has done (if you could post a picture or two that would be great). I would think one might need to put a restriction in the bypass to insure that hot water flowed to the heater core when the valve was open.

I've sort of put off the heater system right now as I have plenty of other things to get done, but I am sure I'll be back to it soon.

(pause)

I went back and reread Goldguru's post and now none of it makes sense.

I think I'm going to have to just try what looks right and then try something else and see what actually works, the whole system function will be different if it it actually a reverse flow too.

I'm going to go try to get the shocks mounted up today and maybe some other drivetrain stuff.

Thanx Guys,
Jaysin

Here is an interesting heater bypass..

http://www.ffcars.com/forums/42-fac...m-cooling-tube-orientation-6.html#post2132835

The vacuum can could be removed and replaced by a cable.

The fluid is either flowing to the core then through the return line or bypassing the cooler and going to the return line.

Of course, it's one more plastic thing to break or leak...

Thanx to all for all the info. I think at this point I will likely make a restricted bypass hose so that when the heater core is open the restriction will force water to want to flow through the core (the path of least resistance and all) and when the valve is closed it will simply bypass. Maybe at a slightly lesser flow but it will still flow.

I have been doing other work on the truck lately, like mounting 4 new Bilstein shocks and working on the flat bead, finish welding the front suspension, etc... When I get back on the engine I will get back to posting. Hopefully I be back to it in a few days.

Thanx,
Jaysin

Hey Jaysin,

Here is a picture of my setup


Flow is coming from top of head in the hose in the top left corner. Yellow lines are when the heater core is closed, utilizing the bypass pipe. Blue lines when the heater core is open flowing into the cab and back down towards water pump. There is a 3 way tee just below the intercooler piping on the bottom right corer. In the tee, the top comes from blue/yellow lines, the right side goes to the reservoir and the left side goes back to the oil cooler/top of thermostat (yellow line on YOUR diagram)



Hope that helps!

p.s. the heater core gets lots of flow, even with the bypass.

ToyotaTDI said:

p.s. the heater core gets lots of flow, even with the bypass.

Click to expand...

So you mean that a restriction in the bypass is not needed, the tee connection of the bypass hose is enough to get the flow to go through the heater core (when open)?

Thanx very much for the picture.

Jaysin

You got it

following your build on the link u posted

traction bars in the works too? why not triangulated 4 link front and rear? seems like u have the know how and fabrication skills and equipment to do so especially if it is an EXPO truck

btw why not a mild steel header? i am planning a alh swap into a mazda or yota soon and would love to have a tubular header i just dont think i have the skills to build one at this momment! the tubing cutter is pretty ingenious! i like it

turdlecharge said:

following your build on the link u posted

traction bars in the works too? why not triangulated 4 link front and rear? seems like u have the know how and fabrication skills and equipment to do so especially if it is an EXPO truck

btw why not a mild steel header? i am planning a alh swap into a mazda or yota soon and would love to have a tubular header i just dont think i have the skills to build one at this momment! the tubing cutter is pretty ingenious! i like it

Click to expand...

As far as the suspension goes... This is mainly going to be a work truck and as such it will see a lot of street time and less hard wheeling time and the four link is just more work and expense. KISS (keep it simple, stupid.) is the name of the game here, plus I want to have it back on the road sooner then later.

Mild steel headers just don't last, especially in turbo applications. I don't want to have to make another 4-5 years down the road. And the cost of building the header from stainless is not that much more then building it from mild steel and having it ceramic coated.

That tubing cutting jig really helped in the next step...

Update.

I have been working away on this and I have the Exhaust system all tacked together and hung. I still need to pull it and weld it completely. It is all 304 SS including the brackets and the V-band clamps. I need to refill my second argon bottle before I weld it up as I need to purge it to get the best and strongest welds I can. Right now it is just straight piped and if it turns out too loud I will have to add a muffler of some sort but for now it's just open. Enough yacking, the pictures aren't the bes as I couldn't really get far enough away laying under the truck.

This is the front where it comes back from the down pipe. You can also see the exhaust brake here.


Crossing over to the driver's side behind the trans/transfer case.


Out from under the cab and up for clearance.


The tail pipe and rear hanger.


Mid hanger attached to the stock rear shock crossmember.


And this is a hard bracket to the transfer case. This supports the down pipe and exhaust brake so that they move as one with the engine/trans. I will likely have one more for greater support of the down pipe off the turbo.


I hope to have the injectors back in a few days and soon I will be pulling the engine and whatnot to install the clutch, injector pump, and pulling the pan to modify the position of the oil drain plug. While it's out I hope to strip the stock wiring that I don't need and paint the engine compartment.

Does anyone have any Ideas on the best way to paint an engine compartment without having to pull everything out of it? Or should I just bit the bullet and pull all the lines and master cylinder, etc., etc...?

Well back to work.

Thanx for looking.
Jaysin

Just read the whole thread. Thanks for sharing. Awsome attention to detail and fab skills. Im working on this into my 84. Its more of a crawler... 4 link rear, locked, 38s. So with that in mind I love the idea the mechanical pump. The more info on that the better. So in the end what wiring will you have for the engine?

I know a local painter guy that does a pretty good job on engine compartments using tin foil to wrap the harness lines etc.....it conforms and comes off easy after the paint is dry....it's quick too

That exhaust turned out awesome. Nice job!

Awesome build man! Glad to see someone else doing all 304 v banded tube work .

Word of caution though, if you don't put one of these in shortly after the turbo, you're going to have major weld cracking issues with any rigid mounts on the exhaust. BTDT, not fun. Verocious Motorsports is my favorite supplier for them. I'd use at least a 6" long one, if not an 8" or 10" if you have the room.

Would the one hard mount not transmit some harmonics into all of the other mounts and potentially to the frame and up?
Matt, would you put that after the hard mount or prior? I didn't use one, but all of my mounts are rubber mounted. Not as much engine movement as in the VW application I see.

Sweet build too. More Yotas!

Thanx for the props guys.

I've never had a problem with a hard mount to a drivetrain part as long as what the hard mount is attached to moves along with the engine. I will take the words of caution into consideration and might put a short flex right off of the turbo.

On a side note I am looking for a small external wastegate for my exhaust brake project. I bought one from eGay and it turned out much bigger then I have room for. Does anyone know who makes or where I could look for the smallest wastegate possible? I have even thought about making one but I don't really want to go through all the trouble.

I'll continue to update as I progress more.

Thanx again,
Jaysin

JaysinSpaceman said:

On a side note I am looking for a small external wastegate for my exhaust brake project. I bought one from eGay and it turned out much bigger then I have room for. Does anyone know who makes or where I could look for the smallest wastegate possible? I have even thought about making one but I don't really want to go through all the trouble.

Click to expand...

I will try to do some research and find a small wastegate. But my question is what will this be used for in conjunction with the exhaust brake? I am currently building an exhaust brake, but have never thought about an external wastegate.

I can assume that you want to make sure the back pressure from the brake does not get above a certain point, is that correct?

Keep the information flowing. I am glad someone else is thinking down the same path as I am with the whole exhaust brake idea. I figure they do it on almost all other diesels.... Why not a Tdi?

dh13 said:

I will try to do some research and find a small wastegate. But my question is what will this be used for in conjunction with the exhaust brake? I am currently building an exhaust brake, but have never thought about an external wastegate.

I can assume that you want to make sure the back pressure from the brake does not get above a certain point, is that correct?

Keep the information flowing. I am glad someone else is thinking down the same path as I am with the whole exhaust brake idea. I figure they do it on almost all other diesels.... Why not a Tdi?

Click to expand...

Well, basically there are two types of exhaust brakes, orifice and wastegate bypass. They both have a butterfly that blocks off the flow out of the exhaust.

The orifice brake, as the name implies, has a hole (orifice) in the butterfly that allows some exhaust to continue flowing regardless of back pressure. Back pressure is dictated by the engine displacement, the RPM the engine is at while decelerating, and the size of the orifice which needs to be large enough to limit the maximum pressure while the brake is actuated. Orifice brakes, therefore make the most back pressure during high RPM deceleration and less as the RPMs drop becoming less and less effective.

A wastegate bypass exhaust brake has a butterfly without a hole and as the name implies a wastegate which is set to a predetermined maximum pressure. This way the back pressure is not dependent on the RPM during deceleration. The butterfly and wastegate block all the exhaust at all RPM until a max pressure is met and then the excess bypasses through the wastegate and the back pressure remains constant even at the lowest RPM.

Now in commercial exhaust brakes the wastegate is built in and just has a small bypass passage built into the housing. I have a 2 1/2 inch Jacob's orifice exhaust brake that I plugged the orifice in and will run a wastegate to control the back pressure. I did the calculations to find out the back pressure that the exhaust valves in the Tdi will lift off of there seat at and will keep my back pressure below this maximum. I will be starting at 30 psi of back pressure and will not go higher then 43 psi, the calculated max is 45-47 (dependant on the age (mileage) of the valve springs). I am hoping that the 30 psi setting will get me enough back pressure to do all the braking I need.

Jaysin

^^^ Jaysin, thank you for the great information. I appreciate the calculations on back pressure maximums.

Keep up the great work. I wish I had the coin to drop on a CNC Plasma table!

-Dan