I cannot figure out my car overheats, thinking I may have a blown head gasket I tested the compression today, I could use some intelligent input on these results!

Motor: LS/VTEC
Head: Bone stock P72
block: B18A, JE 8.9-1 pistons, eagle rods, ACL bearings, stock sleeves, Cometic .053 HG.
Everything else is brand new as well (full-size Aluminum radiator) and OEM Honda (Oil pump, Water pump, thermostat, tensioner, timing belt, misc sensors, etc) Motor was put together by full time Honda mechanic, just turned 1K, Was running perfectly before I put my turbo in (not Water cooled)

RESULTS:

CYL 4 CYL 3 CYL 2 CYL1
1st time: 125 135 140 140
2nd time: 130 140 130 135
3rd Time: 130 140 130 135

Thanks in advance!

 

are you getting any smoke from the tailpipe?
are you losing coolant or oil?
did you....put the dowel pins in back into the head..(sum people forget..)
did you torque the head down right (oem vs arp is dif)

 

try adjusting the valves to see if that helps your compression. re-burp your cooling system. I had the same issue, car was running fine, one day it started getting hot. There was an air pocket that didnt get out... Also sometimes you get a bogus T-stat out of the package... I wouldnt think you poped a HG already if you were just N/A...

 

does the motor only overheat in boost? does it push coolant out of the reservoir?

did you do the compression test with the throttle open?

 

yes, did you have the throttle open?

the numbers look low, i would do a leakdown test next.


did you do a compression test after a few hundred miles to get a baseline? my motors compression kept coming up for the first few hundred miles as i continued to drive it harder further seating the rings.


finally....was it tuned properly?

 

Take into consideration the compression ratio and the headgasket thickness before you guys go calling those numbers low...

 

- is the fan spinning the right way?
- is it overheating on idle?
- did you remove the cover the redirects the air into the rad, or heavily modify the shrouding around the fan/rad?

 

Even if the OP did the compression test when the motor was cold? Compression test should be done when the motor is at normal operating temps, Correct?

 

yes. Should be done at operating temperature.

 

That's what I was thinking.

Do a leakdown test. I have a feeling that isn't your problem. If your car wasn't overheating before you installed the turbo, think of what changed that may have affected the cooling sytem.

 

Thanks for all the responses, I forgot to change my notification settings and thought I had no response!

Lots of good questions, I will work on the car a little more today and see what I can come with, the motor was warm when I tested to compression, I did however have the throttle closed. I'm trying to get a leak-down tester today and I'll let everyone know how it went!

Thanks again,

andy

 

Just in case...

Remove all Spark plugs, disconnect the distributor plug and keep your foot on the gas pedal when you're cranking the motor. I usually do it in intervals of 10 secs.

 

something is definetely going on there... today I worked a bit more on it and didn't get very far.

I rented a coolant pressure tester from Advance and minutes later took it back since the freakin thing was cracked, at first it freaked me out, I placed it on the radiator and pumped 15 psi and saw the gauge go to 0 in about 4 seconds! "Yep, I got a leak" I thought, then I saw the crack!

I took the thermostat out for a test drive, it seemed a lot better for a mile or so, then the temp went straight up as it had done before. so I put the new Honda thermostat in and it overheated idling in about 3 minutes, I felt a lot of pressure on the upper hose but the bottom hose was very cool and very little pressurized. I popped the radiator cap to top it off again and water/coolant just shoots out of there like ol' faithfull at Yellowstone...

Tomorrow I'll do a leak down test and will share the results, I hate to say it, but every symptom points to a blown HG or a crack on the head. Especially since it starts and idles perfectly until it reaches operating temperature, then everything goes to crap... If it s a crack, I'm willing to bet it only acts up when expanded once the temp goes up,

I think I may have to take everything apart! We'll see tomorrow.

Thanks everyone for the input, it's greatly appreciated.

 

honestly my 7.4:1 vitara motor cranked over 155psi, thats with my incapable self assembling it lol.


no seriously there is a nice wide range between upper and lower limits of acceptable compression, with closeness between cyls being the important part. im curious to see how much the numbers come up with the throttle open..


also, 2 years ago i had a compromised headgasket (i thought i put the timing gun on the motor...dumbass me.) the numbers were fine but it would still get the milky oil/coolant **** under the oil cap and valvecover.

original poster, if you have got the motor as hot as it seems, i would make sure to mill the head and check the block, along with a new preferrably oem hg.




oh, in hindsight this is a longshot but it happened to me about 4 years ago, make sure the upper radiator hose doesnt have a bump or high spot in it that would airlock it and not let coolant get out of the head and into the rad.

 

if the top radiator hose is hot but the bottom one is still cool sounds like either the thermostat isn't opening or maybe the water pump isn't working.... start your car and let it idle and crack open the bleeder on the cooling system and see if the coolant is acually even running threw the block.

 

so what was the final outcome?

 

Yeah sounds to me like coolant isn't circulating, or a air bubble stuck in there. If there's no pressure in the cooling system, no white smoke, and no milkshaked oil, it may not be a hg. I always get the car hot, let it warm up and maybe even rape it around the block before I do a compression test. Numbers are very low imo. but the consistancy between cylinders is fairly decent which is the important thing.

Do a test @ wot, with the car hot, bleed it out, make sure the heat is on etc. I wouldn't pull the head just yet.

 

Since he said there was not much pressure on the upper radiator hose, and given the amount of time(very little) in which it overheats You may want to check and make sure the car is really overheating. You may just have a faulty coolant temp sensor or gauge. Not sure if you said if you were running AM or stock. But a bad stock ect will act this exact way. Get a IR heat gun to verify.

 

Been really busy with work lately and couldn't get to the car, tested it again today after getting warm and at WOT, 4@145, 3@140, 2@145 and 1@135

I've bled the system more than once, even got myself a coolant vaccum, it works awesome, it also tests the cooling system for leaks, and of course, there were none... Used dye in the coolant and there were no leaks anywhere.

I've actually changed all the sensors already, (fan switch, TW sensor, sending unit) and same thing... I got one and have used it already numerous times, it's going over 220


I definitely agree the coolant isn't flowing, I'm starting to think the water pump is bad... I've done everything I could including switching the radiator, getting fans that move more CFM, checked voltage in wiring, put my S300 in another car to see if perhaps something had happened to it. Absolutely no change.

Another possibility is a crack on the head above the valves, that would explain why it idles higher when hotter than normal, 3 leak down tests revealed less than 3 and 4% on each cylinder... I guess the head could be cracked affecting the idle when hot due to expansion...

THanks again for your time!

 

Did you check for air leaking into the cooling system during the leakdown tests? That's one of the best ways to diagnose a leaking head gasket.