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Old 08-11-2011, 08:56 PM   #1
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Default Engine overheats under boost

The setup is a BP 1.8 dohc engine, T3/T4 .50 trim, 2.5 exhaust system, afpr, etc.

The wideband readings are consistent in the 11.5 to 12.0 afr @ 15 psi / 14-15 afr when cruising, conservative ignition timing. Spark plugs are NGK6 gapped to .040, new oil pump, all forged internals [email protected] pistons bored to 84mm.
(with a 83mm stock HG). That is why I have another thread about the HG question.

I have been driving the car like this for a while with no problems whatsoever, but today went out for a spin and did a 2nd to 5th gear pull shifting at 7,000 rpms and then all of a sudden the temperatures went past halfway to almost 3/4 toward the H. The needle never hit the H, I have the fan to turn on manually, so I always have it on whenever I do test / tuning passes or on very hot Florida days.

The engine also overheats if I stay in heavy traffic for too long. (I think the engine does not like the .040 gap)

What would be causing the engine to overheat?

There is no smoke coming out of the tailpipe, oil is not milky, coolant is green with no oil residue. From what I have read when googling the title of my thread, most point to a blown HG, but seems weird as no smoke comes out of the exhaust, spark plugs look clean with no water residue.

The only thing that has changed is the spark plug gap. Before it would never overheat on back to back passes with .030, decided to open the gap as long as I had no blow by and afrs stayed withing parameters. Would that affect the heating department.
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Old 08-11-2011, 09:09 PM   #2
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What is your ducting like? Do you have the stock lower tray on? When was the last time you burped the radiator? How much water is in your overflow tank?
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Old 08-11-2011, 09:11 PM   #3
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Stat sticking a little? Water pump impeller failing?

I think most of us run our plug gaps .25-.30in. with the ngk bkr7e. At least with the stock ignition system.
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Old 08-11-2011, 09:21 PM   #4
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I put fresh coolant and oil/filter yesterday. I had to tear open the trans for a new clutch and on the meantime did a complete tune.

The overflow tank is almost full. No ducting, I removed all the plastic, and lost it on my last house move. Have to go to the jy and get all the covers.

Now that I remember when I was changing the engine oil a little bit fell on the water pump belt, maybe it is slipping, but the strange thing is even at idle or on heavy traffic.

I thought I could go as much as possible on the gap as long as there is no blow by and the afrs are 11 to 12 at full boost.

I got to admit that is the only thing that has changed after the tune, that I adjusted the gap to .40.
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Old 08-11-2011, 10:24 PM   #5
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Well, nevermind...

Waited til the engine cool off to remove the spark plugs. Took a peak with the flashlight and chambers 2 and 3 have a strong coolant smell with some water residue on the piston dome.

Chamber 1 and 4 seemed "ok" not such strong coolant smell and no coolant residue. Most say all four spark plugs have a whitish brown black color.









1 to 4 from left to right.

Gotta love the Kodak Easyshare, after 5 years and it is cake to take macro pics.
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Engine overheats under boost-100_1930.jpg   Engine overheats under boost-100_1928.jpg   Engine overheats under boost-100_1925.jpg  

Last edited by mazpr; 08-11-2011 at 10:26 PM. Reason: JDMPOWELOL
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Old 08-11-2011, 11:14 PM   #6
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I did a compression test:

Piston #1- from 180 to 165 psi

Piston #2- from 180 to 165 psi

Piston #3- from 180 to 160 psi

Piston #4- from 180 to 170psi

I drained all the coolant out of the radiator, left the cap off in the rad. Opened the throttle body with a long screwdriver to do the compression test, disconnected the fuel pump so no fuel would dump into the chambers when testing compression. I hope it is not a bent valve, although I prefer a bent valve than having to tear apart the engine again.

Not sure if it because of seized piston rings, or because it is losing compression through the blown head gasket. I am so pissed off, after having the engine dialed and now this...
And engine that is 2 months old on forged internals.

After I got the engine from the machine shop, the fuel pump died. Then when I was going to install the new flywheel, the wrong one was sold to me and the car would not engage in any gearl. Had to open the transmission again, grab the old flywheel etc. Then the oil return line fitting on the oil pan started leaking, and the gasket sealant used was crap and leaked behind the rear main seal. Because I left the car on the driveway for a year, the injectors were clogged, had to send them to injector-rehab. It started leaking oil from the valve cover gasket, changed it and now it is leaking from one of the cam seals. Installed braided lines in the front brakes and the clutch line, a few weeks later the brake master cylinder died. I tell you I am almost hitting borderline and throw the car off a cliff.

I hope the loss of compressilon is from the blown head gasket.
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Old 08-14-2011, 06:44 PM   #7
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Well, back on the road, was pissed off so I installed 2 metal head gaskets, compression went down of course.

No overheating at full boost, none at heavy traffic. Decided to go with the NGK7 with .025 gap, little less on the ignition timing, and done.

Also for now lowered boost to 10 psi instead of 15. Changed the annoying cam seal and no more leaks. It started raining so way to much tire spinnning, not good for the engine so got to wait til tomorrow for better weather.

It seems the FMIC is a magnet for cops cause it has happened twice that I pass cops and they lower the speed.
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Old 08-15-2011, 05:05 AM   #8
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Quote:
Originally Posted by mazpr View Post
Well, back on the road, was pissed off so I installed 2 metal head gaskets, compression went down of course.
You installed two head gaskets at the same time? As in you stacked them?
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Old 08-15-2011, 08:58 AM   #9
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I'm still trying to wrap my head around that one.
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Old 08-15-2011, 12:02 PM   #10
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Quote:
Originally Posted by mazpr View Post
Well, back on the road, was pissed off so I installed 2 metal head gaskets, compression went down of course.


***** u best be trollin
Seriously.

Put your ducting back on. I took mine off to make my own, so I've been driving without it. Even with a fuckhuge radiator my temp needle still creeps after 3-4 minutes of hard driving.
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Old 08-16-2011, 11:14 AM   #11
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Bump for lulz.
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Old 08-16-2011, 02:41 PM   #12
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This is the deal, **** heads, I live in Jacksonville, lets meet up to some asz raping...

Yesterday shredded a Mustang Gt500 by half a car, AZZholWlwes!


Bring me one of your stupid megaSGUKKIRT miatas to have some fun, Ahhh!

I have been flamed before but no diYHcked assHasshole dares to match up...
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Old 08-16-2011, 02:46 PM   #13
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Quote:
Originally Posted by mazpr View Post
This is the deal, **** heads, I live in Jacksonville, lets meet up to some asz raping...

Yesterday shredded a Mustang Gt500 by half a car, AZZholWlwes!


Bring me one of your stupid megaSGUKKIRT miatas to have some fun, Ahhh!

I have been flamed before but no diYHcked assHasshole dares to match up...
I lol'd IRL
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Old 08-16-2011, 03:23 PM   #14
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Quote:
Originally Posted by mazpr View Post
This is the deal, **** heads, I live in Jacksonville, lets meet up to some asz raping...

Yesterday shredded a Mustang Gt500 by half a car, AZZholWlwes!


Bring me one of your stupid megaSGUKKIRT miatas to have some fun, Ahhh!

I have been flamed before but no diYHcked assHasshole dares to match up...
I'll accept that well worded duel, but we have to go from a rolling 130.
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Old 08-20-2011, 08:15 PM   #15
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If this isn't just a troll... I am guessing that you obviously have an intercooler... Do you have A/C? I was rapidly overheating before I deleted mine, putting some space between the IC and rad.
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Old 08-20-2011, 10:31 PM   #16
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make sure you have a radiator. then double check to see if there is oil in the engine.
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Old 08-21-2011, 01:24 AM   #17
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Quote:
Originally Posted by Clos561 View Post
make sure you have a radiator. then double check to see if there is oil in the engine.
Just add a third head gasket.
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Old 08-21-2011, 01:29 AM   #18
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I am gonna assume that was a joke.
If your headgasket was blown and leaking coolant in to the cylinder i would expect to see a brighter white ceramic on the plug for that cylinder. That along with the matching compression leads me to believe that you got a leak elsewhere. I could always be wrong though.
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Old 08-21-2011, 07:51 AM   #19
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Allright, my bad for such response as I was caught in a bad day and should not have posted such stupid replies.

Once again I will rewind:

On my first setup, grabbed an engine from a junkyard, bought main, rod, piston etc rings, bearings and refreshed the engine myself. Gave it a honing with auto zone tool. Some dishwasher soap and engine degreaser and as good as new. Slapped some Miata [email protected], a Kia cylinder head, basic bolts ons and ran it like that all motor for 4 years. No ring gap, piston to wall clearance, crank measurements, plasticgage (whatever it is called) was done, I just bought the rebuild kit and installed, and like I said it ran solid from NA, all the way to boosted like that. At the beginning I had no idea about ring gapping etc so that is why it was not done.

For a while decided to test a ported head with some custom cams from integralcams (which by the way everything was free, as it was more test and tune). I needed to go programmable to get the most of those cams, but MS at the time was in baby steps and universal ECUs I had no clue and way out of my budget. If I decided to keep the cams then of course I had to pay for the custom cams. The test bed cylinder head port work ok, still found that for NA the stock one gave me more low end for NA application.

Before moving back to the stock CH, I took the stock 4 ply metal gasket, broke the rivets, and remove the two outer layers to bump a little the compression and force overlap as at the time I had no cam gears. I know is ghetto and retarded, but believe me or not never had any cooling issues, no leaks and compression was raised by 5 psi. I left it like that with the two plya modded head gasket and ran it for the next 2 years or so with no problems at all.

Then decided to go boosted, slapped the turbo, all necessary components etc, but I left the engine untouched. So I went from NA to turbo with the same combination, same pistons, ghetto two ply gasket, and like that I was able to run 15 psi with a ghetto piggy back SAFC, with 11-12 afrs with 87 octane. The clutch wa slipping badly as I still had the stock Dakin pressure plate w/ 4 pad sprung disc. Which means it would over-rev if launched to hard on 1st and 2nd gear.

One thing I should have changed (at least) from the NA setup was the aluminum crank pulley, before I went turbo. Some told me to go back to the stock one as there were stories of premature oil pump failures due to the increase vibrations the oil pump was going to be put to. Well, one day boosting at 15 psi and all of a sudden a grinding noise and when I look to the mechanical oil gauge it was reading zero psi. Immediately shut off the engine and pull at the first parking lot with the vehicles momentum.

When the engine was tore open, the cast pistons had no damage even with 3 bent rods and a oil pump failure. Like I said, I only knew I had 3 bent rods because the oil pimp failed and I tore it open, and the engine ran fine so after a while I did not do anymore compression tests. I would feel a slight vibration, but I would always blame it that I needed to fill the engine mounts. FYI, also the oil return line was leaking, oil pan was leaking a little to, rear main seal, but nothing major to worry about as it was not much. Also, during this whole process of swapping CH I would reuse the same gasket and CH bolts, and never ever resurfaced the CH, and still no problems at all.

Allright, came here to MT and saw the Supertech and M-Tuned reviews and decided to go ahead to go the forged route. This time I went more conservative, less compression ([email protected]), colder plugs NGK7 iridium with smaller gap, and always run 93. Bought new fuel pump as the old one was a knock off of a Walbro, new oil pimp, rings, bearings, all the stuff. Almost forgot, new disc and performance pressure plate so no more slipping and over-revving.

This time decided to play it safe and let the machine shop do the work, cleaning, assembly everything. And just in case sent the 550cc injectors back to cleaning and calibrating

Got the engine back, all new seals, all good to go... same setup but with lower compression and no more leaks, slipping clutch etc. Cranked the engine, and starts leaking near the alternator side and right underneath the distributor between the head and block when under boost. Called the machine shop and the guy tells me bring the CH for resurfacing, and suggests to get ARp bolts, and do not reuse the head gasket. So I follow all his recommendations, slap everything together and still leaks...

To eliminate any other possibilities, a turbo jacket was installed, and thermo tec heat wrap on the turbo mani, wrapped all the way from the downpipe to to the firewall.

Call back to the machine shop and the owner asks for my invoice number to check if the engine was decked, and I quote "By looking at your invoice you did not request to get the block decked"...

I dont know much about machine work and I came to learn about decking when he told me those words, and immediately I googled it. So he built an engine without checking if it needed to be decked! Its like building a cylinder head and not advising the customer a magnaflux and pressure test before continuing to do any good on the CH.

He suggested to re-torque the arp bolts just in case which of course I did. The leaking stopped, at least visually, but one day at 15 psi and the engine went super hot doing an all gear pass from 1st all the way to redlining 5th. Engine overheated and afrs hit 13s and 14s low.

What cause the lean reading was not my tuning, was the overheat. Opened the engine and there was a leak between piston 3 and 4, and obvious sign of water. The water reservoir tank was full to the top. Ok I know about the SAFC, but this has nothing to do with the current leaking, water contamination into the piston chambers. What was happening is the coolant instead of recirculating properly, it was just doind everything minus it basic job of cooling the engine.

FYI, I also installed a Summit electric fan which I had it connected to a switch to turn on manually, so I would always have it on during heavy traffic and a few minutes before if I was going to boost the engine.

****

So on my previous setup that I built myself, a ghetto hone, knock off fuel pump, leaking oil engine, slipping clutch, 2 ply resused metal gasket, resued cylinder bolts, higher compression 210, cast pistons, stock electric fan, and the engine never overheated. In fact I could leave the engine running on heavy traffic without turning the fan and it would not reach half way on temps as long as I would not boost. 3 bent rods, failure oil pump, and I can still use the Miata cast pistons, and the cylinder walls are like new. Could run 15 psi back to back passes on NGk6 with 87 octane and redline it to 5th gear and all good.

But with this engine, all kinks worked out, all new stuff, lower compression, shaved cylinder head, colder plugs, 93 octane, new metal gasket, arp, same tuning with SAFC and wideband, etc etc and it overheated on a 5th gear redline pass blowing up the gasket, which by the way was the gasket to engine block side. An engine built by a machine shop, with all ring gap, clearances taken care of, which this is the shop that outsource the engine build process. So they did the machine work, but the build process was done somewhere else. To this day they do not want to tell me where this build shop is at...


I have shown the engine block, piston, CH, and gasket damage to a few friends who have boosted cars, and one is a mechanic, and agrees the block needed to be decked and the shop does not want to admit it.

Thats it for now, good morning everyone!

Last edited by mazpr; 08-21-2011 at 08:03 AM.
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Old 08-22-2011, 05:38 PM   #20
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Sure sounds like you got the intake manifold gasket on backwards. thats what i did and it leaked everywhere from the area you describe. What head gasket did you end up using?
You might try having the block and head checked for cracks. Oil pump failure and 3 bent rods would definatly give me caue to have everything magnafluxed.
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