Hey everyone,

Getting started up on here again now that I picked up another Fiero and hopefully will learn a thing or two.

I was driving an old 85 2M4 with 360,000km and showing no signs of dying but sadly moved to the other side of the country and left it behind.

I found an 86 GT out here but had a pretty bad cold the day I looked at it and didn't look over the car nearly as well as I should have. I was told all the car needed for an insurance inspection was a new windshield and the parking brake. I've already had to replace both rear calipers and and the pads, and now I'm on to the cooling system as on my first drive home with the car I noticed the heater core is toast. I've had a replacement on order for well over a week now but I've been having terrible luck with the quality of service at the parts stores here. Driving it in the meantime, I got air in the lines one day and it's been acting up ever since. One of my co workers recommended using some heater core stop leak (the silver stuff) until the replacement came in and from what I've been reading online after the fact I'm not sure it was such a good idea.

What seems to be happening now is that on my morning drive of about 25 minutes the car gets warm but no problems. In the afternoon when it's warmer out and I'm hitting a lot more traffic lights and construction and near the end of the drive when I'm stuck at traffic lights the temperature gauge starts bumping up between the quarter and halfway mark which it never did before the air got in. at the same time once it starts going up like that the oil pressure light will go on while i'm idling at ~800rpm at the lights. All it takes is getting it up to 1000-1200 rpm and the light goes off. Any time the light goes on though, I've just gone and parked the car to cool it down for a while. No problems starting it up afterwards and the oil pressure is better again until the car gets hot. I called a rad shop in town and the guy seemed pretty convinced that the silver stop leak wasn't clogging anything and that it was more likely air in the lines. I thought air in the lines tended to make the temperature gauge fluctuate up and down rather than jsut a gradual increase? Anyways if you guys could help lead me in the right direction I would be greatful as my experience doesn't go too far beyond brake jobs and oil changes.

Here's a little more info on the car if it will help:
-140,000km on the body
-from what I've been told by the previous owner the engine is a 3.4 block from a Camaro that was just rebuilt, put all new bearings in and a comp cam. it still has all the original intake and top end off a Fiero
-currently has 5W30 in it. (likely going to switch over to 10W30 but would like to find the rest of the problems first)
-no leaks that I can see coming out of the water pump
-I removed the coolant overflow and noticed where the hose attaches there is just a big gob of silicone and a zip tie. tried draining the extra coolant in there through the hose and nothing came out. I don't have a spare ziptie if I rip it apart right now but is there some sort of check valve in there or should the tank and tube flow freely?
-cooling system is pressurizing but I haven't noticed the rad fan turn on by itself yet. (it turns fine when the AC is turned on though)

Any and all advice would be greatly appreciated!

See my Cave, Coolant Fill and the rest of cooling section.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Well you can fix things one at a time or do the whole system. When it comes to the cooling system, I refurbish the whole system and be done with it. First thing is to get the overflow working. Get a hose from Any parts store; new tank and or cap from the Fiero Store. Replace the thermostat, radiator cap and fill cap in the rear (cheap insurance). Rock Auto has heater cores and stock parts. Check all your hoses and replace as necessary - Fiero Store has them if needed. When you replace the heater core, vacuum out the air box to make sure it's nice and clean. (there is a long metal clip on the left side of the heater core - do not bend it too much because it Will break). You can also remove the blower fan (in the front trunk) without too much trouble and clean out debris. There might be a filter screen in there that you can remove, clean and replace.

Last step, check your radiator - if the side tanks are plastic, get a new radiator with metal side tanks - the plastic ones Will crack and leak and leave you stranded. If your radiator already has metal tanks, I'd take the car to the radiator shop. Have them pull the radiator, remove the side tank and clean the coolant tubes/passages. Replace the radiator and flush and fill the system. I also add a bottle of water pump lube. This whole process should be about $100- $150 from the radiator shop.

[This message has been edited by PaulJK (edited 05-23-2014).]

OK I have never heard of any radiator shop, "recommending" any kind of stop leak, unless they are even more crooked than most others, see they all clog up every tiny little hole in the system, it is a temporary fix at best. At worst it will clog up things so bad that even a flush and fill may not fix unless done repeatedly. Something tells me the original owner used that stuff already and that may be the very reason you are getting no heat. Think about how a stop leak of any kind works, it plugs up holes and it doesn't have a clue what ones need to be clogged up so it plugs them all.

Whenever we fill a Fiero cooling system, you must burp your baby and I am not being funny here, think about you kids when they were on the bottle and if you didn't get the gas out by burping them and how cranky they got. Well in our cars it is a lot similar only they get cranky in the form of over heating and that can be even harder on a car than a kid.

read the ogres cave and listen, he has some great advise there.

if you want to do a back yard mechanics flush and fill of your heater core take both heater core hoses off the heater core and cut the end off a garden hose and clamp it onto one of the heater core tubes and another section onto the other tube and into a clean white 5 gallon bucket. You must use hose clamps, you must or you are going to get a hose blow off the cores tube. Now place one hose in to 5 gallon bucket and have a helper hold that in there or it may blow right out of it when flushing. I use a small hose shut off on the end of a good hose so I am not destroying a good 50' hose and then after the lever shut off, available at any hardware store or China Mart for 50 cents, then a hose clamp onto a small section of hear hose to the core with another clamp on the core tube.

now charge your garden hose and then attach the shut off to the core, open the valve slowly, it shouldn't take a few seconds for the water to circulate threw the core and out to the water bucket. When it does start flowing have your helper watch what comes out of the other tube, I bet its all junk, if anything comes out at all. that is most likely the stop leak, or could even be peace's of the old hoses that have deteriorated over the decades.

I didn't see if you said there was a leak under the dash, if there was that is your core leaking. they usually leak inside the passenger compartment. now if no leaks or no flow into the bucket open the valve a little more. eventually you will get some flow into the bucket. make sure you don't open the valve all the way until you get some flow into the bucket or you risk doing even more damage to the heater core.

once you get some good flow run it for a while until about a half a bucket of water then open it up all the way and let it run for a second or so and shut it off. now check the floor inside the if its wet you have a leaking heater core, if not its fine. check the 5 gallon bucket for crap.

Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

Hey Disrupted Ether,

I see you're here in Edmonton. I can recommend a really good shop that can get this done for you. They have worked on my car and treat me more than fairly.

PM me if you want the info.

Check for crushed cooling pipes and that the fan is coming on at 180 or 200 degrees. If you are hotter in stop and go than while driving then it could be fan is not drawing air, and that fan is VERY effective (like 20-30 degrees in just minutes of coming on). Burping is big - If you need to, jack the back up so that the engine fill is very high and gets the air out before the coolant warms up too much and overflows - also do this with the t-Stat out or you will never get air moving. This is why you can not burp from the front radiator fill.

Oil light at warm low RPM = weak oil pump or worn main bearings (other bearing could be to blame, but crank bearings are usually the case). First short term/ medium term solution is higher viscosity oil - 20-50. You can drive a long time in this condition, but you will eventually replace bearings or oil pump.

Thanks for all the replies guys.

The heater core was definitely shot from day one. I had a three hour drive to get it home when I bought the car and halfway through that I had coolant dripping on the passenger floor mat and greasy fog on the glass. It wasn't the radiator mechanic that recommended the stop leak. The day the overflow ran dry and the system sucked in air I had a co-worker recommend the stuff at the same time I refilled the system. The rad guy only said that he couldn't see the stop leak being the cause of the overheating or clogging anything major and the problem was more likely air in the system.

I finally got my replacement heater core after 8 days of waiting and that article posted on here was really helpful for the job. The old hoses came of super easy, all I had to do was grab them with vise grips, crush the old tubes slightly and twist. The only part that didn't go according to plan was the previous owner had installed the subwoofer wrong. I had to take out most of the dashboard connecting points to get enough movement in the dashboard to pull out the subwoofer bracket near the passenger interior light. Judging by the corrosion and condition of the old core I'd say it had been bad for quite some time. Got the new one in now though and burped the car a few times then gave it a 10 minute drive with no problems. Let it sit overnight and burped it some more today doing that rad cap/thermostat cap trick from Ogres Cave. Also pulled off the top heater core hose like it said on there to slowly let any air out. I had coolant come out right away though so I'm hoping all is well there now. The overflow seems to have fixed itself too from when I had cleaned it out the other night. I had given up then when nothing at all was coming out through the tube but yesterday when I went to pull it out of the car to try again I had a gusher come out. Not sure what that was all about.

I think I'm going to go through a bunch of the other stuff you guys listed but my finances are going to be pretty tight for a few weeks. I think the next bit will be to take the car in for a coolant flush as the heater core is fixed and I'd rather have that stop leak out of the car than in. Going to be doing a drive to the airport in a few hours, got my fingers crossed that the heater core and air were the only problems.

next time you have a leak problem in the cooling system, try cracking an egg and putting that into the cooling system than using a stop leak you buy at the parts store. that stuff is like pouring cement into the cooling system. and egg will work temporarily and eventually just disappear unlike stop leak. Some of the passages in the cooling system are so small that a stop leak product will plug up things that you need open and that is not good.

Steve

[This message has been edited by 84fiero123 (edited 05-26-2014).]

Stop leak etc won't work when heater core or radiator are the problem.
Metal is too thin to get a good seal.
If it does, pressure will try to open the leak again.

Stop leak does work on big gaskets etc. Like a weeping head gasket.
GM and others have installed them at factory on some engines. GM had TSBs so Dealers won't flush system thinking got contaminated coolant.

[This message has been edited by theogre (edited 05-26-2014).]

Yeah I don't plan on using the stuff again and once the cash comes in I'll take the system in for a flush.

Did the drive to the airport yesterday, took ~40 minutes. Temp gauge didn't go past the quarter mark and oil pressure stayed at the halfway point of the gauge. As soon as I stopped the car at the airport though the oil pressure light went on. I got out of the airport and the light went off while driving but wasn't as high as it was on the way down. Parked the car for half an hour or so and it was fine again on the way home, no oil lights at idle and the temp gauge was only 3 notches up.

I read an article last night the said faulty timing can cause low oil pressure in Fieros. The car does smell like it's running a little rich and doesn't have the most consistent idle rpm. (usually ranges from 700-1200rpm but usually 800-1000) so maybe it could be timing? It also said the 3.4 block has a different oil flow and can play a factor and sometimes high volume oil pumps are a wise option. I can't see it being any bearings or gaskets gone as the engine was just rebuilt.

I fought the whole low oil pressure light for yeara, i installed a mechanical gauge and found the sending unit was garbage. I drive an 87 gt, i upgraded to the new 88 style sensor per ogres cave. No problems whatsoever on 240k on 10w30 oil. If you replace get an acdelco sending unit and pigtail. Standard producta pigtail isnt water repellant, shorted out old sensor after a week.

Well I've been going through the car slowly and had a couple different people take a look over it. I also found posts on here and another forum of the previous owner and some of the work he did on the car. Turns out the camshaft lobes disintegrated in the car and that's why he rebuilt the car. I've got the cooling issues all sorted out but the oil pressure still drops when the car gets warmed up. The best solution I can think of is that when I asked him he didn't replace the oil pump when he rebuilt the car. Maybe some metal from the cams got in there and damaged the pump enough that when the oil warms up the pump can't keep the pressue up?

Here's his post, it probably explains things better than I can.
Previous owners forum post

He also used SBC bearings for the camshaft. It's a little beyond what I know with cars but my dad was saying the grinder he used for a channel could be causing problems. Any thoughts? Here's some pics of what he did with the cam bearings.

SBC cam bearings

I guess where I'm at now and where I would like some opinions is now that I found a mechanic that isn't going to charge $1000 for the job what oil pump do I go with? I've been reading on here and other forums and will keep reading more but there seem to be mixed opinions. Most people seem to say the 3.4 block requires a higher volume pump than what the stock 2.8 one can put out. Do i just throw in a factory 3.4 one? or maybe a high volume 2.8 or 3.4 one? and what pickups do you use and is it really neccessary to tack weld it to the pump?

Oh and the sending unit has been upgraded to the 1988 version. I had the rad shop stick on a mechanical gauge and test it and according to them it was reading 20psi cold idle and then went down from there when car warmed up. I have a feeling the engine was still a little warm when they did it though as the pressure is normally fine on the guage when I start it after sitting overnight. I'll see what happens with a new AC delco sending unit as the one in there right now died after being only a month old... We'll see.

Thanks for all the help everyone!