[skippy89]

Alright guys I have a question, and hope to get some help here. I have 1989*Chevy truck, brand new GM Good Wrench 350 long block assembly roughly 2-3,000 miles on it. Topped off with an Edelbrock Performer TBI intake, new 195 degree thermostat,holley TBI, and all new sensors. The problem at hand is this, i just replaced my thermostat because I noticed she wasn't getting up to temperature, and that fixed the cooling problem. I lost some coolant changing the thermostat, and went to top it off and bleed the air out of the system. no matter how hard I try, I can't get the air out of the system. It's not the usual big air bubbles I'm used to. The air bubbles are more like a "Jacuzzi", small bubbles that wont stop coming up through the radiator and seem to foam up. I just replaced my oil with no signs of coolant, and I don't notice anything coming through the*exhaust. Another problem I feel is related to this, is a rough idle. When I first ran the engine for roughly 1,500 miles my idle was strong, no surging. But I took the truck up to the mountains, a good 150 mile drive, and returned with a surging idle. I started replacing sensors, one by one that were from my old engine, thinking they had there last straw after the 200,000 miles they suffered on the last motor but there was no change. When I first start the truck in the mornings, she has a strong steady idle for the first five minutes exactly. Then after that five minutes has past the idle starts to go up and down varying RPM's at no specific fluctuation range, this will continue while in gear, but no as noticeable, but it is slowly getting more noticeable now. My theory, is that I have a small leak in my*head gasket, small enough to only let gasses past, and not allow any coolant to pass through. And the reason my idle starts to freak out after five minutes, is because, of the expansion of the steel once warmed up, allows the gasses to pass. What do you guys think? has any body had a similar problem?

[S10 Racer]

Was the stock motor a 350 or 305?

[skippy89]

Stock motor was a 350

[64nailhead]

Not sure how the Holley TBI works, but based on you say it idles properly when cold and then poorly when warm, I'd check vacuum at cold idle and then hot idle and see what the difference is. Does the Holley system work on maf or map sensor.

After rereading your post, do you have a complete Holley EFI system or a Holley replacement throttle body using the GM ECM. If the latter, then I would definitely guess that you have an intake leak, a bad IAC.

That's my guess. Some more info would be helpful.

Regarding the head gasket, are you using coolant? Are you getting excessive pressure in the cooling system? Anything smelling funny out of the exhaust? Smoking white? Any sludgy residue on the dipstick or oil fill cap? If no to all of those, I would say your headgaskets are fine.


Good Luck.

[ssmonty]

Does the coolant level keep dropping? If it does take a look at the spark plugs. If one or two look different than the others, it could be a sign that they're getting affected by coolant(cracked head/block/blown or leaking gasket). Could narrow down your search.
If the level stays consistant you might try drilling a small hole(1/8" or slightly smaller) in the thermostat body to let air out.
Like 64nailhead suggested, get a vacuum gauge on it and record the readings. Disconnect the IAC when its cold just after its started. Note the results. Let it get cool and reconnect. Start it and let it warm up, wait until it starts surging again then disconnect the IAC again and note the results. Be ready to shut it off if it starts to race or stall.
Good idea to check fuel pressure cold and hot as well just to rule it out.
Whats the temp. gauge doing?
ssmonty

[skippy89]

Originally Posted by 64nailhead

Not sure how the Holley TBI works, but based on you say it idles properly when cold and then poorly when warm, I'd check vacuum at cold idle and then hot idle and see what the difference is. Does the Holley system work on maf or map sensor.

After rereading your post, do you have a complete Holley EFI system or a Holley replacement throttle body using the GM ECM. If the latter, then I would definitely guess that you have an intake leak, a bad IAC.

That's my guess. Some more info would be helpful.

Regarding the head gasket, are you using coolant? Are you getting excessive pressure in the cooling system? Anything smelling funny out of the exhaust? Smoking white? Any sludgy residue on the dipstick or oil fill cap? If no to all of those, I would say your headgaskets are fine.


Good Luck.

The Holley TBI is just a bolt on replacement, same as the stock, just a larger cfm. I haven't checked the vacuum yet, I've been meaning to do that for quite some time now, ill see about checking it after work though. And it is a stock MAP system. I'm using green coolant in the system, and I can't seem to keep it full I'll check that again after work. And no I don't see anything mixing in my oil, or dipstick. I'll have to pull the valve cover to see any farther with my set up. As far as exhaust goes it's hard to tell because it's been cold out lately, and I get the usual white exhaust in the morning. Although now that I think about it, it does take awhile for that white exhaust to come, I don't get it as soon as I strat up

[Northern Chevy]

One thing you have going for you assuming it is a mechanical issue or at least I believe so, that it is a GM Good Wrench engine because the dealer where I am claims that any shop in North America can do an R & R with another new engine and GM will cover the shop costs. Thats even if you installed it initially and just don't feel like going through all the work yourself ... all over again. Of course it always sounds good standing one one side of the parts counter discussing it but in practice ... well that I can't say !.

As I am sure your aware, it can take a few heating and cooling cycles to finally get the coolant to settle in at a level but I would be concerned too if I saw a lot of bubble activity at the rad and more so if you see a constant flow of little bubbles reaching the reservoir as that just shouldn't happen once the system is full.

Just a shot in the dark item you could try in the same manor as the IAC, when its cold unplug the O2 sensor and see how the engine responds once it gets warmed up as it can't go into closed loop then and would remain rich. I don't know if its possible for an 02 sensor to go wacky like that or the system that is reading the 02 output. Definitely not an educated guess on my part though.

A question I thought I would throw out there for others familiar with the pollution testing stations in the states { there is no such thing in Alberta }, with the testing equipment can they sense if coolant is in the exhaust gas by chance ?.

[64nailhead]

Seeing that it's a stock setup, is you CEL on or been on recently?

Other than that, do the basics. If you are driving this everyday, then verify coolant usage. The steam out of the exhaust will be noticeable different if it has coolant in it.

X2 on SSMonte, check fuel pressure along with vacuum.

Did you adjust the TPS when you put it on the new throttle body? How did you set the timing?

[ssmonty]

FWIW my moneys on a bad head gasket. I don't see how bubbles get into the radiator if it were a bad intake gasket. I did however have a bad intake gasket on a 4.3L that caused coolant level to drop. I'm thinking that alls ok(except bubbles in rad) until the engine gets hot. Then the coolant gets pressurized and is pushed into the chamber causing odd combustion/pull on next intake charge. Vacuum gauge should be fluctuating. Just a guess?
Any chance there wasn't enough antifreeze in the coolant mix so that a small amount in gasket pocket could have froze/expanded gasket enough to cause leak?
I'd look for an odd colored plug/plugs and perform a leak-down test or just hook up some compressed air(120psi) into spark plug hole(piston at TDC on firing stroke so that valves are closed) and listen for noise in intake/crankcase or bubbles/pressure in radiator.
Hope its not, but you should check if you can't find a vacuum leak on intake somewhere IMO.
Hope some of this helps one way or the other.
ssmonty

[skippy89]

Originally Posted by ssmonty

Does the coolant level keep dropping? If it does take a look at the spark plugs. If one or two look different than the others, it could be a sign that they're getting affected by coolant(cracked head/block/blown or leaking gasket). Could narrow down your search.
If the level stays consistant you might try drilling a small hole(1/8" or slightly smaller) in the thermostat body to let air out.
Like 64nailhead suggested, get a vacuum gauge on it and record the readings. Disconnect the IAC when its cold just after its started. Note the results. Let it get cool and reconnect. Start it and let it warm up, wait until it starts surging again then disconnect the IAC again and note the results. Be ready to shut it off if it starts to race or stall.
Good idea to check fuel pressure cold and hot as well just to rule it out.
Whats the temp. gauge doing?
ssmonty

Yes my coolant keeps dropping, I can't keep it full. And when I turned off the engine, with the cap off, coolant launched out of the radiator and went everywhere. i haven't checked anything with the electronics/vacuum, (and I'm waiting on a fuel pressure guage) , for surging issues yet. Because I am now staring to over heat from a short ten minute drive to work, it's getting up to the second to the last line I want to guess 240 since the last one is 260 and middle is 210. And i try to top off the radiator but it keeps surging and pushing all the fluid i add out, I've almost went through a jug trying to do this. And I'll check my spark plugs shortly once the headers cool down.

[skippy89]

Originally Posted by 64nailhead

Seeing that it's a stock setup, is you CEL on or been on recently?

Other than that, do the basics. If you are driving this everyday, then verify coolant usage. The steam out of the exhaust will be noticeable different if it has coolant in it.

X2 on SSMonte, check fuel pressure along with vacuum.

Did you adjust the TPS when you put it on the new throttle body? How did you set the timing?

No check engine lights at all, originally was throwing a code for my TPS but that stopped once i placed the new one on. I struggled to adjust the TPS with the ohm gauge when i did it, so i set that by ear. And timing, originally, I set it by unplugging a wire and setting it at 0. I remember at one point i went to check my timing after all this happened. I unplugged the wire, and the truck wouldn't start. Then i started it, and unplugged it and it went into a violent fit until it finally died, even after i plugged the wire back in after it was running. I haven't tried messing with that since that episode, because it ran fine was i cleared the computer. I noticed today after work i started the truck to warm up, and there was no white smoke, but after idling roughly 6 minutes it started puffing out a small white cloud, from both pipes ( they are joined by a small 2 inch H pipe) and what i would say is excessive moisture, enough to make my hand moist when holding it in front of the exhaust, along with the ground. then i drove it to the part store to pick up a block tester, and i didn't notice any white puffs when i parked and checked while idling. And coolant usage is enough that i can't really keep it full.

[skippy89]

Northern Chevy:

Well that's good to know, I was curious about how there warranty worked. I really don't feel like going through all that, I hardly had the time to install the engine, with my work schedule. There's no way i would have the time to tear it down, even though i hate anybody else working on my rig.

I'll try toying with the IAC and O2 once i get the cooling problem taken care of

and as for the emissions, nearest emission vehicle test station is 40 miles away

[skippy89]

[QUOTE=
Any chance there wasn't enough antifreeze in the coolant mix so that a small amount in gasket pocket could have froze/expanded gasket enough to cause leak?
I'd look for an odd colored plug/plugs and perform a leak-down test or just hook up some compressed air(120psi) into spark plug hole(piston at TDC on firing stroke so that valves are closed) and listen for noise in intake/crankcase or bubbles/pressure in radiator.
Hope its not, but you should check if you can't find a vacuum leak on intake somewhere IMO.
ssmonty[/QUOTE]


I mix my coolant to water 60/40 so there shouldn't have been to much water, although for about three weeks we were sitting at -10 in the mornings and 15 all day, so it was pretty cold. I'll be checking the plugs in a few minutes hopefully. I can't do leak down test right now, but I'll try to do a compression test soon. And I originally checked everywhere for a vacuum leak with carb cleaner, but found nothing.

[Northern Chevy]

Just to clarify, have you been doing this a few times now in trying to add coolant by removal of the cap from the hot engine while its running { which is very dangerous in itself for being horribly burned }, then shutting the engine down ? If so, that coolant "launch" as you put it when an engine is shut down, is exactly what will happen with a properly operating engine. Once the coolant flow is stopped by the water pump not circulating it, it will super heat by a hot engine and boil and just come frothing out violently.

The only way I know to add coolant to a mechanically sound { not leaking or head gasket failing } engine so that you don't reintroduce air pockets from super heating coolant by releasing the pressure is to NOT touch that rad cap when the engine is up to operating temperature and just make sure you have plenty of coolant in the overflow reservoir and let it self siphon into the engine as it cools. Then after many hours of cooling, its ok to remove the cap and see if there is an air space left and if so, top it up and squeezing and releasing the top rad hose can aid in working out a little air ... its slightly helpful I find sometimes. The heating and cooling cycles of the engine are typically what is used to completely fill an engine so there are no pockets of air in the heads as its that air which will cause a lack of heat transfer and the engine will run hotter and can damage it if it gets out of hand.

Also its not really recommended to mix coolant that strong unless you live in a VERY cold climate where the coolant will jell in the rad by supper cooling as a 50/50 mixture is generally ideal as a balance between boil over and cold temperatures and the reason being, too high a coolant concentration does not transfer heat away from the engine or reject it out of the rad by air flow as well. Sometimes more is not better and that happens to be the quirk of antifreeze. Water is the better heat transfer agent but it has too low of a boil point and no rust inhibiting properties or ability to lubricate the water pump seal.

Please don't think I am coming across as anything other then wanting you to stay safe, and pointing out there is a reason why a rad cap is designed to build that pressure which is, to keep the boiling point of the coolant at a higher temperature ... as soon as you remove that cap, the boiling point drops below the actual temperature of the engine and you saw the results of that with coolant spraying your nice clean engine compartment with slime everywhere !.

Hmm, hope that came across as intented !.

[64nailhead]

Originally Posted by skippy89

Yes my coolant keeps dropping, I can't keep it full. And when I turned off the engine, with the cap off, coolant launched out of the radiator and went everywhere. i haven't checked anything with the electronics/vacuum, (and I'm waiting on a fuel pressure guage) , for surging issues yet. Because I am now staring to over heat from a short ten minute drive to work, it's getting up to the second to the last line I want to guess 240 since the last one is 260 and middle is 210. And i try to top off the radiator but it keeps surging and pushing all the fluid i add out, I've almost went through a jug trying to do this. And I'll check my spark plugs shortly once the headers cool down.

Are you saying that you had the cap removed with engine running and when you turned off the engine coolant then shot out. Or it did it shoot out after you turned off the engine and then took of the pressure cap?

Did the coolant usage problem develop after you replaced the thermostat? If yes, then remove it and run it with the t-stat out to see what happens. If the head or head gasket is bad, then it will still push coolant with the t-stat out. If it is overheating, then SSMonty is right on the money about checking leak down, plugs, etc..

With that being said, if you end up thinking it is a head or head gasket, before you pull the heads, take a really good look at the intake gaskets for leaking in the valley. Also I'd get a hold of whoever you bought the long block from and make sure you complete any testing they require for warranty because all the testing is over once the heads are removed.

Good luck, hoping you just have a dud t-stat