Cooling issues on new turbo build

[Zmanco]

I finally have the engine together and towed it to the muffler shop where we put a 3" exhaust on yesterday. Everything is running fine except for one big thing: the temps just continue to climb until it overheats.

 

I've changed the thermostat with a known good one with no effect.

 

I've run the engine with the cap off to purge air and can see water flow once the thermostat opens and the radiator is definitely hot.

 

It took about 2.5 gallons total to fill, so I don't think there are any significant air pockets left.

 

So far I've taken it out for a few drives longer than several minutes. The second time I was able to drive about 5 miles with the temp staying at 180, but then it started to rise and within a few more miles was nearly boiling over.

 

My thoughts are that exhaust gasses are passing into the cooling system.

 

A little more background: Besides adding the turbo, the only changes to my old NA motor are these:

- I swapped the old N42 block for an L28ET block. It had almost no miles on it, so I didn't do anything to it except pull the oil pan to confirm all looked good and clean inside.

- I swapped my shaved P90 head and drilled holes for the #5 and #6 cylinder cooling mods. Both of those run to a T and then to the bottom of the thermostat housing.

 

I figure the two most likely sources of exhaust gasses would be a failed head gasket, or damage from when I drilled the holes for the 5/6 mod. I was very careful to not let the bit go past the hole and damage anything inside, but now I'm second guessing myself.

 

Before I pull the head off, are there any other things anyone can suggest? Simple ones are better as I'm really not looking to pull the turbo off with the engine in the car. And is there a simple way to confirm exhaust gasses in the cooling system?

[Guest Rolling Parts]

What's the mixture looking like? You might pull some spark plugs and see if they are white (too lean, too hot).

[FlatBlack]

What's the mixture looking like? You might pull some spark plugs and see if they are white (too lean, too hot).

 

Why would that make it overheat?

 

 

Before I pull the head off, are there any other things anyone can suggest? Simple ones are better as I'm really not looking to pull the turbo off with the engine in the car. And is there a simple way to confirm exhaust gasses in the cooling system?

 

Can you pull the plugs for the bypass and get a flashlight to see if you did any damage?

 

And pull the spark plugs to see if there's any coolant still in the cylinders if you're worried that that might be the case.

 

My Z31 overheated after I changed the alternator, it turned out just to be a bubble in the system.

[Guest Rolling Parts]

Why would that make it overheat?

.

 

He's just installed a turbo with no indication he installed an intercooler. White plugs means too hot. Heat is transferred to the coolant and shows on the temp gauge. A richer mixture will lower overall combustion temps and then show up as "tan" plugs.

 

Since he also said no other changes to the NA engine, I'm curious about the injectors, any changed to the AFM, or if he's block the NA dizzy to keep it from advancing. Too lean and too advanced is too hot.

[TrumpetRhapsody]

He's running megasquirt, I'm sure the mixture is fine.

[FlatBlack]

He's just installed a turbo with no indication he installed an intercooler. White plugs means too hot. Heat is transferred to the coolant and shows on the temp gauge. A richer mixture will lower overall combustion temps and then show up as "tan" plugs.

 

Since he also said no other changes to the NA engine, I'm curious about the injectors, any changed to the AFM, or if he's block the NA dizzy to keep it from advancing. Too lean and too advanced is too hot.

 

I understand how to read plugs. See this please v

 

He's running megasquirt, I'm sure the mixture is fine.

 

Seeing as you don't know much about his setup, maybe you should read up on the motor before posting? From the Original Post:

 

A little more background: Besides adding the turbo, the only changes to my old NA motor are these:

- I swapped the old N42 block for an L28ET block. It had almost no miles on it, so I didn't do anything to it except pull the oil pan to confirm all looked good and clean inside.

- I swapped my shaved P90 head and drilled holes for the #5 and #6 cylinder cooling mods. Both of those run to a T and then to the bottom of the thermostat housing.

 

He's got a CAS Dizzy and a Turbo block, not an N/A dizzy and block. Please read the OP thouroughly before you post.

 

He's been using MS for a while now:

http://forums.hybridz.org/showthread.php?t=136198

 

And has a wideband:

http://forums.hybridz.org/showthread.php?t=120990

 

I mean how many people have overheating issues with running lean or advanced spark? Most people blow head gaskets or damage their motors.

 

Sorry to hijack Zmanco, hopefully this is something easily remedied.

[Zmanco]

Hey thanks to all of you for the ideas. I had a chance to check the plugs and they look normal. I had forgotten to check the timing calibration/setup with MS and it was a few degrees retarded, so that's not it. I don't think it's a timing issue at this point.

 

And yes, I did add an intercooler - sorry forgot to mention it. But the overheating occurs even when I short shift with a light throttle staying out of boost so don't think it's heat from the intercooler.

 

But.... I forgot to mention that I still have the hood off. Do you think that's the issue? It will idle and cycle the fans on and off and keep the temp normal just as it always did. But a slow drive around the block (25 mph) will cause the temps to start to climb.

 

I'm sure the hood affects airflow through the rad, but I've seen others drive with their hood off and don't recall hearing about cooling issues. I'll put the hood back on, but can't do that for a while until I have another set of hands.

 

In the mean time, any other thoughts?

[TrumpetRhapsody]

Just as a baseline reference, how hot is "overheating". You say the temps climb, but how high do they get before you start getting worried?

 

I personally don't think it's an issue with the hood being off, but I could be wrong.

 

 

There is a small possibility that your waterpump needs to be replaced. It could be that at speed the radiator is doing a good enough job of cooling the poorly flowing water, but that around town it just can't keep up. You might try checking the condition of your water pump as a last resort.

[Zmanco]

Just as a baseline reference, how hot is "overheating". You say the temps climb, but how high do they get before you start getting worried?

On the first drive it actually boiled over (water only). The radiator cap is new. The temp gauge was into the red.

 

There is a small possibility that your waterpump needs to be replaced. It could be that at speed the radiator is doing a good enough job of cooling the poorly flowing water, but that around town it just can't keep up. You might try checking the condition of your water pump as a last resort.

I thought about that. But I moved the pump over from the old engine and it only had about 20k miles on it. I thought that when they failed, it was by leaking, or the impeller breaking off the shaft. In this case there is definitely water movement when I look into the radiator through the neck, although at idle it's more of a vibration, but at 2k rpm it's quite visible.

[RTz]

Thick skin, Boy's. Thick skin.

[Zmanco]

So I put the hood back on and no more boiling over, although the engine definitely ran hot even though it's cool today and I was just driving in mild traffic. I'm going to pull the AC core out and see if that's the culprit.

[Guest Rolling Parts]

So I put the hood back on and no more boiling over, although the engine definitely ran hot even though it's cool today and I was just driving in mild traffic. I'm going to pull the AC core out and see if that's the culprit.

 

 

Radiator? Fan shrouding?

[Zmanco]

I removed the AC condenser and things are better. Now and then the temps go above 200 but it's not tied to how hard I drive the car. I suspect the issue now is the #5/6 cylinder cooling mod I did dumps the hot coolant from them right into the lower thermostat housing which is causing the sensors to report wide temperature swings that may not represent the real temp of the coolant throughout the engine.

 

Tomorrow I'll reroute them to the other side where the coolant enters the timing cover.

 

Side note: boost is addictive

[FlatBlack]

Hey, just wondering, but wouldn't that defeat the purpose of the bypass if that water doesn't go through the radiator, just right back into the block?

 

I'm not 100% sure that's right, correct me if I'm wrong.

 

Is there any way you could just run it to the upper housing [tap it I guess] and dump it after the thermostat, that way it still goes through the radiator?

[pallnet]

A few things that come to mind.

1)Adding an IC is one more thing for your fan to pull air through before cooling the rad.

2)Fan clutches get weak and they look like they are still working

3)An electric fan on the front side of the rad. worked awesome on my car. My IC was the same size as the rad.

4)I have seen waterpumps that looked perfectly fine but when hot the impeller would spin freely from the shaft.

5)A 4 core rad. helps bigtime. The nice looking aluminum ones on Ebay that are made for SR20DET powered S13's will fit in the S30 with custom mounting brackets.

 

Hope I was able to help.

pallnet

[Daeron]

A few things that come to mind.

1)Adding an IC is one more thing for your fan to pull air through before cooling the rad.

2)Fan clutches get weak and they look like they are still working

 

If you can at all, feel for spots in your radiator coils that are less hot than others. One of those non-contact thermometers from Harbor Freight is great for this sort of thing. I am wondering about a partially obstructed radiator coil.

 

To check your fan clutch, you need to first try to rotate the fan blade by hand when the engine is cool. It should rotate freely enough.. NOT rotating freely while cool with the engine off is not a significant problem (at least, it wouldn't contribute to overheating.) Then, make sure the fan blade at least looks like it is spinning when the engine is hot and running. Finally, and most importantly, shut the engine off with it good and hot, and see if you can spin the fan blade freely NOW. at this point, the fan clutch should be holding the blade firmly to the water pump hub, which should be held pretty much immobile by the belt around the crankshaft pulley.

 

The fan clutch lets go of the blade when cool, and grabs it when hot. Even if it LOOKS like it is spinning when hot, if you can rotate it freely it is bad and bneeds to be replaced. The work involved in moving air over your radiator is still work; it requires force, which is a drag, which means any slippage WILL decrease the amount of work done ie, how much air the fan actually moves.

 

If that is all a little condescending, I apologize, but I prefer to spell it all out rather than spit out a short version that might leave questions unanswered.

 

Other thoughts: water pump impellers are not all created equal.

 

A final CR estimate was never given; the original post in this thread almost implied that the original NA engine was refreshed with a turbo block but never specified pistons, and then a shaved P90 was mentioned but we are unsure whether that was coming, staying, or going. In short, I was wondering what pistons you had (probably turbo dish pistons, right?) and whether you are running an uncut P90 or if you have the shaved one on? (.080"?) I bring this up because a shaved P90, even with dished pistons, should bring CR up to around 8.5:1. Mid eights is certainly a realm where others have gotten savage detonation in the past, so it could be a situation where you need to tweak your tune. So it is worth clearing up the ambiguity.

 

Good luck!

[bigal]

I agree with Daeron, you probably need to rule out any kind of restriction in the radiator first by checking for temperature differences between the top and bottom, then check the fan clutch. What i do sometimes is roll a couple sheets of newspaper up into a cylinder and lightly touch the fan blade while the car is running, if it chews up the paper the fan clutch is probably ok, if the paper stops the fan, replace it

[woldson]

Hummm.

 

To post or not to post...

 

Naw, seems like there is good enough people helping.

 

Yes, I see the irony in a no post posting.

[Zmanco]

Thanks guys for the further ideas. I didn't list all my engine details because I didn't want the post to grow so long no one would read it, but let me fill a few things in:

 

- Stock turbo block with dished pistons

- 2 12" e-fans and no shroud

- P90 head that was shaved .080" yielding 45.5 cc chambers. Daeron, you are right that CR is around 8.4.

- Radiator is the old MSA 4 core and except on hot track days before I installed the oil cooler, has never had any problems cooling the car when it's in motion.

- I had an existing megasquirt tune that I modified for turbo (changed Reg Fuel to fit new 440 cc injectors, etc) I purposely went very conservative on timing and rich on mixture (based on what I saw others doing with similar setups) for my baseline and only had a little detonation at 4k and up under full boost. I was overheating even under light throttle steady state cruising.

- Water pump came from the old engine and is supposed to be the "preferred" one (I think the mfr's name begins with a P?)

 

Hey, just wondering, but wouldn't that defeat the purpose of the bypass if that water doesn't go through the radiator, just right back into the block?

 

I'm not 100% sure that's right, correct me if I'm wrong.

 

Is there any way you could just run it to the upper housing [tap it I guess] and dump it after the thermostat, that way it still goes through the radiator?

I thought about that, but the cover is rather thin to be putting an NPT into. Plus, the heater core dumps into the same place and if the heater valve is open, but the other sliders don't vent air over the heater core, then it's a pretty similar situation, isn't it? In any event, it's an easy experiment so I'm going to try it later today.

[slownrusty]

Daniel - I was worried when I read your post with the fear that you had a tiny bit of combustion pressurizing your cooling system as this has happened to me before and its the worst feeling having to go through the effort of pulling the motor, redecking the head and or block and new a headgasket etc etc.

 

Anyway and luckily it seems this is not your problem.

 

Pallnet's suggestions should be seriously considered. You have seen my white ZX Turbo. I am running a very thick intercooler and a thick oil cooler and also twin electric Flex-A-Lite fans thermostatically controlled on a semi-custom aluminum Arizona Z Car radiator. I also removed my AC condensor.

 

My car never sees past 180-190F it runs beautifully cool (I have about 80-90 miles on my new set-up, maybe more), in fact the electric fans earn their keep though and run frequently. Its comforting to hear them kick on as the L6 is not tolerant of high temps or temp spikes. I lost my faith in the clutch fan many years ago.

 

I hope that helps, contact me if you want to chat further as we are only 45minutes from each other.

 

I ecstatic you got your car up and running and I hope you guys had a great time yesterday at Tynan's (any pics?). Sorry I was a no show.

 

My best,

Yasin