Overheating on cam break in. Glowing Exhaust

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Overheating on cam break in. Glowing Exhaust

Post by nosigma »

Engine Specifications
21CC dished RPM machine pistons
.040 overbore
63.8-64.5 CC chambers
.041 gasket
.005 off deck
SCR 9.33-9.24
DCR 8.01-7.93
Quench .048
Cam is Comp Cams 68-232-4

Radiator is stock from the 199CID 6 that was in it when I had the264 CID 10:1 big cammed triple weber motor in it, never over heated on me.
Water pump is Flow Kooler 1747 rotation is CCW and is correct (unless they sent me the wrong pump).
Injectors are 27lb Bosch (blue ford) EV1
Fans are Ford Contour with an electronic controller. Fans kick in (soft start) at 180 degree. I need to verify that they are ramping up to full speed.
T-Stat is 195 deg Stant.
Exhaust manifold is stock Cherokee opening up to 2" tubing and a flow mater 40 muffler.

I do not have an adjustable MAP or Fuel Pressure Regulator.

Engine has two temperature sensors. One is a Borden tube sensor set into the block. The capillary tube is no closer than 2" from the exhaust (one place) and is typically 5-6 inches away. The second sensor is the stock Rambler sensor in the 4.0 head at the back of head. I used the stock sensor so it would work with the stock gauge.

The engine fired right up on the first try. I brought the engine speed up to 2000-2500 and after about 6 minutes it began to boil over.
I adjusted the fan turn on speed, let it cool, filled the radiator back up and tried again. Same result after about 5 minutes.
Third try it overheated after about 6 minutes. It was dusk and I noticed a glow from the engine bay. The manifold was cherry.
In every case the cylinder head temperature gauge (stock) barely got to warm. The block mounted gauge sat at 100 for a while and then steadily climbed up to 230 very quickly. On the second try it jumped very quickly from 230 to 270, it began to boil over and I shut it down immediately. After just a couple minutes of being shut down the block temp drops back to 180 or lower.

I let the car sit over night. Did a compression reading this morning. (~15-20 minutes cam break in so far)
1 200lbs
2 200lbs
3 194lbs
4 200lbs
5 195lbs
6196lbs

Checked the distributor phasing. Center of rotor is exactly 3cm from the left edge of the slot for the rubber grommet.
At 700 rpm idle when cold the timing floats from 15 BTDC to 19 BTDC. After its warm (not hot just starting to warm up) the timing is very stable at 18 deg BTDC.

Wide Band 02 sensor readings:
700 rpm idle: 16:1
During light acceleration, no load from idle up to 2000-2500 rpm AFR was 15:1
During cam break in from 2000-2500 rpm AFR varied from 13.9:1 to 14.3:1
After overheating it will NOT start up again until it cools off a bit. The AFR is up around 30:1 until it cools for 10 minutes or so.

Here is my list of things to do in sequence.
1) Replace the T Stat (get a Robertshaw)
2) Verify that the fans are coming up to full speed.
2) Check cam timing. Strip down the front of the engine, pull the radiator and put the degree wheel back on it. I have the Cloyes 3 position crank gear. I installed the cam straight up (at least thats what my notes show). But who knows.

Ideas?

John
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Re: Overheating on cam break in. Glowing Exhaust

Post by nosigma »

Correction: Deck height is .005, not .005 off of the deck.
Cylinder head is 62.8 CC (cut .010 off the head)

John
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Re: Overheating on cam break in. Glowing Exhaust

Post by BADASYJ »

Man thats a head scratcher, never seen or heard of the manifold glowing when not under load.I would double check the timing while thr front of the motor is apart. How did your plugs look? Sounds like you might have air trapped in the head, thats why the temp sensor in the head not reading hot. Is the coolant flowing thru the thermostat ? Did you build pressure in the cooling system?
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Re: Overheating on cam break in. Glowing Exhaust

Post by SilverXJ »

Its common for the manifold to glow during the cam break in. The over heating is not. Possibly an air pocket. Possibly thermostat. Does it have a jiggle valve or a 1/8" hole to bleed air?

That idle AFR looks a bit lean. The rest not bad. Don't know what that 30:1 means though.
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Re: Overheating on cam break in. Glowing Exhaust

Post by jbxx »

Did you pull the temp sensor in the back of the head after putting the water in?
These engines typically get an air bubble in the top that should be bled ( per factory repair manual ).
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Re: Overheating on cam break in. Glowing Exhaust

Post by Cheromaniac »

nosigma wrote:Fans are Ford Contour with an electronic controller. Fans kick in (soft start) at 180 degree. I need to verify that they are ramping up to full speed.
T-Stat is 195 deg Stant.
Your fan on temp. needs to be set at least 15*F higher than the t'stat opening temp., and the fan off temp. needs to be set at least 5*F higher than the t'stat opening temp.
Yor cooling system may indeed have a large air pocket and the easiest way to get rid of it is to jack up the front of the Jeep, remove the radiator cap, start the engine from cold and let it idle. The coolant level will drop initially so SLOWLY top it up while gently squeezing the upper radiator hose. Once the bubbles stop and the coolant starts rising up the radiator filler neck, put the cap back on and take the Jeep for a test drive. Make sure there's enough coolant in the overflow reservoir so that it can be sucked back into the radiator when the engine cools down.
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nosigma
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Re: Overheating on cam break in. Glowing Exhaust

Post by nosigma »

I appreciate all the replies.

Air Pocket:
The engine is in a 66 Rambler convertible (see pic below). The top of the radiator is about an inch higher than the top of the valve cover (motor sits real low). When I filled it I pulled the sensor and let some water flow out (had to pull the cap to let water flow out). Front of the car was up about 8" on jackstands during all the motor runs (bleeding hydroboost and PS during cam break in) but the cap was on and the water level was well above the top of the head. I just ran down stairs, pulled the senor out, got a little flow, loosened the cap and got a brief geyser. I will let it run with the heater on and the radiator cap off for a couple minutes at idle on the next start up.

Plugs:
The plugs where white with just a hint of brown or grey on a couple of them. The motor had only run 13-16 minutes on the first three starts before I pulled the plugs the next day. They where not glazed and there were no black speckles (burned).

Fan Temp Settings:
I set the fan "on temp" at 180 using pot of hot water and a thermometer. It only has an on setting. The unit ramps up the fan speed over the next 30 degrees to 100%. Not sure if backing it down is going to help matters. Once I have the overheating sorted out I will increase the fan on setting so it doesn't turn on at highway temps.

Did it build pressure:
It did build some pressure since it didnt start spewing fluid until it hit 240-260 and it definitely came out under pressure. However I think the cap is weak, its much easier to seat than my XJ's cap (16lb). Rambler cap is 13lb. Sort of stupid but Gee the cap worked fine on the last motor, why not on this one? Its on the list to replace before the next start up.

Flow Through the T Stat?
I have no idea. With just a few minutes on the motor and almost all of it at 2000-2500 rpm (with me watching gauges) except for when I put the timing light on it I did not have a chance to look in to the radiator (top center cap, top tank) to see if there was flow.

T-Stat (Jiggle or bleed hole)
T-Stat is a Stant 195 degree unit (same as stock 4.0) it has an 1/8" bleed hold.

AFR:
It is bit lean, but its not burn a piston under no load lean. An adjustable MAP will trim that out. The 30:1 AFR happened when I tried to restart it immediately after it overheated. Engine would not start at all at that sort of AFR. It cooled down (on the block temp gauge) very very quickly. Honestly it seemed to cool off too quick which is why I thought initially the Borden tube might be touching or very close to the exhaust manifold and causing the super high temps. As I said earlier the Borden tube is clear of the pipes and since it really did boil over there is no question that it did get stinking hot really fast. After about 15 minutes of being turned off the engine was fairly cool, block temp under 150 and it would fire right up at a nice 13.9-14.1 idle AFR.

I am going to do all the easy stuff (cap, T Stat, e fan speed check)before the next start up then if I still have a problem I will tear down the front of the motor to check the cam timing.

Keep the ideas coming. I really appreciate it.

John

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Re: Overheating on cam break in. Glowing Exhaust

Post by SilverXJ »

I had a flowkooler water pump with that plate riveted to the fins once. The engine would over heat with it. I replaced pretty much everything in the cooling system and it would still get hot. I put a stock pump back in and the over heating issue went away. Just a thought.
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Re: Overheating on cam break in. Glowing Exhaust

Post by nosigma »

SilverXJ

Thanks for the reminder on Flow Kooler. I have read the same thing from other 4.0 and stroker owners. There are plenty of people who have run that pump with no problem too. I was hesitant to install a Flow Kooler pump because of that chatter and experiences like yours. When I pull the fans I will swap out the pump, its quick, easy and takes one more questionable item out of the equation. So my next actions are:

1) New Cap
2) New Robertshaw T Stat
3) Check fan flow under full power
4) Replace the Pump.

I will do all four at once and then test again. I can test the T Stat and fan speed before the restart so I will know if either were faulty. So if the four changes fix the problem it will be either the cap or the pump that were the solution if the TStat or Fan check out as good. If it cools off after the next running I can swap caps and see if it overheats again and determine what was the culprit. If it still overheats then I am left with the Cam timing. Sounds like a plan.

John
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Re: Overheating on cam break in. Glowing Exhaust

Post by SilverXJ »

When I had the flowkooler it took it a while to start to get hot.

After you get it all back together check the temp of the upper and lower radiator hoses. Upper is in, so it should be how, bottom is out so it should be a bit cooler, but not cold when the engine is up to temp.

Your AFR don't look too bad, the 16:1 at idle is a bit lean and a map sensor adjuster will not correct that, but at idle that isn't much to worry about. Aside from the 30:1 (i'm not sure what is happening there) they are fine.

What is the history on the injectors? Salvage yard find?

What about the head bolts? How many times have they been reused?

As far as the air in the head, its still possible if the engine isn't significantly angled. I usually jack my XJ up until the tires are a foot off the ground and let it sit that way over night after an engine install. That way any air pockets in the coolant can bleed out. Using that method I have had to add very little coolant afterwards.

I may have missed this, but what about your distributor indexing?
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Re: Overheating on cam break in. Glowing Exhaust

Post by nosigma »

Silver XJ,

I will take the questions in order then a comment on a discovery......

After you get it all back together check the temp of the upper and lower radiator hoses. Upper is in, so it should be how, bottom is out so it should be a bit cooler, but not cold when the engine is up to temp.
I will check them. I bought my neighbor a non contact pyrometer for his birthday last year, I will ask to borrow it back.

Your AFR don't look too bad, the 16:1 at idle is a bit lean and a map sensor adjuster will not correct that, but at idle that isn't much to worry about. Aside from the 30:1 (i'm not sure what is happening there) they are fine.
I will keep my eye on AFR, but for now I agree its not a problem. When I put it under load is when I will really start sweating AFR values. I have all the parts to log rpm and timing. I can tap into the MAP sensor, TPS and IAT as well with the system since they are all 5V.

What is the history on the injectors? Salvage yard find?
Injectors are rebuilt and "balanced" units from one of the NON e-bay companies (web site & a history).

What about the head bolts? How many times have they been reused?
Head bolts are ARP and were used on the 258 build (previous motor), reused once (on this motor). The long stud on the front is off of the stock XJ that I got the core from. Excellent service records (book was in the glove box in the salvage yard). The motor was quite a find.

As far as the air in the head, its still possible if the engine isn't significantly angled. I usually jack my XJ up until the tires are a foot off the ground and let it sit that way over night after an engine install. That way any air pockets in the coolant can bleed out. Using that method I have had to add very little coolant afterwards.
I just drained the system in prep for pulling the fan, radiator and T Stat. Easy enough to drop the rear when I fill it up.

I may have missed this, but what about your distributor indexing?
Indexed and checked a couple times. Used the method of measuring 3cm from the left edge of the square grommet notch in the dist body to the center of the rotor at TDC. Rotor is past the #1 cyl plug wire contactor as it should be.

I ran over to parts store to use the radiator cap pressure checker. They didnt have one. I had them pull a new cap off the shelf to compare spring pressures (13lb system). I mentioned earlier that the cap spring pressure seemed a little light. It was very light compared to a new cap. Bought the new cap and used a digital scale to see what the opening loads (not pressures) were on the old and new caps. New cap measured 20.5lbs open. Old cap measured 8 lbs open. Radiator throat is 0.95" in diameter. For the new cap this works out to 13.5psi. For the old cap this works out to 5psi. If you check a boil over chart for 50/50 mix the boil over is 220deg F for 50/50 at atmospheric pressure. At 5psi its 235 (about when I started seeing a little fumes and drips at the cap) and 259 deg with a 13lb cap. Now increasing the boiling point will not make the radiator fluid any cooler, it will just run hotter before boiling over. That said, increasing the boiling point will prevent hot spots from forming where the fluid has turned to vapor in the engine and this will increase heat transfer to the coolant and make the engine (the metal) cooler. I dont think this is going fix the problem but it will at least let me get accurate temps (no question of vapor on the sensors once bled).

John
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Re: Overheating on cam break in. Glowing Exhaust

Post by jsawduste »

Maybe a dumb question but are you running a fan in front of the vehicle to push air towards the radiator ? Or relying on strictly fan pull to draw air through the radiator.

Whenever I`ve done a cam break in I always put a big box fan to blow towards the vehicle.

Another thought, was the 4.2 a CW rotation and now the stroker is a CCW ? If so then the fan itself is different for CW vs CCW. You can readily see the difference in the blade shape between the two. Using a shroud ?
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Re: Overheating on cam break in. Glowing Exhaust

Post by jsawduste »

jsawduste wrote:Maybe a dumb question but are you running a fan in front of the vehicle to push air towards the radiator ? Or relying on strictly fan pull to draw air through the radiator.

Whenever I`ve done a cam break in I always put a big box fan to blow towards the vehicle.

Another thought, was the 4.2 a CW rotation and now the stroker is a CCW ? If so then the fan itself is different for CW vs CCW. You can readily see the difference in the blade shape between the two. Using a shroud ?
Reread your post. Forget my comments on the CW and CCW fans. See you are running an electric fan. :boom:
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Re: Overheating on cam break in. Glowing Exhaust

Post by nosigma »

Quick update:

Fans:
Fans are hooked up correctly and are pushing air at 22kts (my anemometer reads in kts) or about 26mph which should be good enough for a no load cam break in.

TStat & Cam timing check coming up this weekend...

John

jsawduste: no worries. I do the same thing all the time.
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Re: Overheating on cam break in. Glowing Exhaust

Post by Cheromaniac »

nosigma wrote:Fans are hooked up correctly and are pushing air at 22kts (my anemometer reads in kts) or about 26mph which should be good enough for a no load cam break in.
Yeah, that's plenty of fan capacity. Considering that the radiator surface area is ~2.5 sq. ft., that's equivalent to an airflow of ~5700cfm.
SilverXJ wrote:I had a flowkooler water pump with that plate riveted to the fins once. The engine would over heat with it.
I've been through two Flowkooler pumps and never had a problem with either of them, except that both only lasted ~60k miles each before they began to leak from the weep hole. So much for the lifetime warranty! My original stock pump lasted 112k miles. I'm now running a stock pump and the engine runs just as cool as it did with the Flowkooler. In fact the only parts of my cooling system that aren't stock are the JET 180* t'stat and the dual electric fans.
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