I have a big problem with my lower intake manifold (LIM).
It has gotten some small cracks as I have replaced the fan temp sw . But I haven´t tightened the fan switch too tight, because it has cracked already at the first three turns. The thread of the switch wasn´t completely turned into the LIM, nevertheless it cracked instantly! (there was a "cracking" sound as I screwed the sw into the LIM after a few turns)
I may have used too much Teflon tape on the thread!? Nonetheless the wall thickness around the fan switch thread hole seems to be quite small and is predestined to brake.
I think most of us would just replace it, as there are plenty of good used ones around... but I notice you're in Austria. Might be more difficult to find over there!
Teflon tape is not used because you need an electrical connection to ground. Perhaps it also caused the crack, but it seems unlikely. The threads are not clean, and therefore probably a bit under size. You can weld and re-tap the threads, but if you can arrange for shipping, it would be best to get another one.
Teflon would not break whatever. Over torquing will.
Find a good welder/machine shop or get a new manifold
------------------ 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)
Amazing how fast you guys reply here and how easy it is to get replacement parts in US!
Here in Austria I can´t even get SAE bolts, so it´s nearly impossible to get an LIM from a Fiero.
I think in whole Austria only 5 Fieros are driving around here!
Alternative for getting used US-car parts are junkyards in Germany, but of course prices are a way higher than in USA.
Due to very high shipping costs importing parts from US usually only makes sense for big consolidation orders. In case for the intake mani shipping costs at airmailpost (sale-tax free forwarding company in Delaware) will cost about $59 with NPFS (No Postage and Free Shipping) printing service (LIM weight 4kg). In addition to this I also have to pay for national shipping costs which I pay to the seller. That means the price of the LIM must be quite small that the overall costs will not exceed $100!
@ fieromatty: Can you make a good offer for me?
BTW, I also have lying around an old engine. A Firebird 3.4PR engine which I've bought for the engine swap (plans for the future).
The Camarobird LIM should also fit the Fiero, right?
But my 3.4 Firebird engine doesn´t have the holes for the cold start injector and the cold start injector temp switch. Therefore I´ll lose the additional fuel amount which might be needed for cold starts. Does anyone know if a Fiero starts wo a cold start injector in Austrian climate conditions (2°C at the moment)
@theogre: I haven´t over-torqued the temp fan sw. There was still plenty of clearance between the bolt head contact surface and the LIM and then there was the cracking sound.
I guess that I have used too many Teflon tape layers on the thread.
FYI, in order to get ground I´ve cutted through the Teflon tape on some areas of the thread.
If you can get a shipping price from colorado 80831 to wherever you are and grab a quote. I would be glad to just give it to you if you pay for the shipping.
I haven´t over-torqued the temp fan sw. There was still plenty of clearance between the bolt head contact surface and the LIM and then there was the cracking sound.
I believe that's where you went wrong... the "head" of a pipe-thread fitting does not get seated when tightening it. The hole is tapered, and it's just the threads themselves which seal the fitting.
[This message has been edited by Patrick (edited 01-17-2015).]
Likely was already cracked by whoever did work in past. First pic of crank says the crank is old... likely Sound was second crack started. My guess is big crank is full of coolant leak stop etc or didn't grow enough to leak coolant and full of road crap etc.
is common to see this because many Mechanics and DIY will wrench down fittings/sensors... They easy break aluminum but ever cast iron can fail. Not just engines... many plumbers over torque pipes and fittings too.
Oh **** , these threads are tapered? I haven´t recognized this and thought it needs to be sealed with Teflon or a special thread sealant.
Of course with tapered threads correct tightening specifications are very important. But it I think the max. force which I´ve applied on the wrench (lever ~ 20cm) as the LIM cracked was just about 100N, not more which feels like nothing. (bolt thread was still halfway from overall thread length out of the LIM surface)
Then the applied torque would be approx. 20Nm - which isn´t much I think.
Does anyone know tightening specs of the fan temp sw for avoiding future damge on these aluminum intake mainis?
According to the Ogre's link, a 3/4" pipe thread is 78 ft/lbs. (I think that' hole is about 3/4") That converts to 105Nm. I doubt if GM had a separate spec just for that sensor.
An interesting side-note....Never use a torque wrench to tighten NPT fittings! The preferred way is to turn the part with your hand, and then turn 1.5 to 3 revolutions.
[This message has been edited by Gall757 (edited 01-17-2015).]
Originally posted by Gall757: According to the Ogre's link, a 3/4" pipe thread is 78 ft/lbs. (I think that' hole is about 3/4") That converts to 105Nm. I doubt if GM had a separate spec just for that sensor.
An interesting side-note....Never use a torque wrench to tighten NPT fittings! The preferred way is to turn the part with your hand, and then turn 1.5 to 3 revolutions.
NPT threads torque depends on many things. Ft/Lb is only a rough guide at best. Very important---> The ft/lb doesn't mean much because of so many sealer formulas... X brand can lube the thread more/less then Y brand.
Most sensors/senders have brass bodies. Takes little effort to tighten brass in Al Cast or Steel parts.
Teflon tape: use 2-3 full wraps of tape depending fitting size. Tape should not be used on senders that ground thru the threads. Sometimes the tape gives a poor or no electric connection. Small size or ground thru thread is best to use paint on pipe dope.
today I have measured the NPT-thread diameter of the fan temp sw. The thread dia. of TFS-4 SW starts with 16 mm and increases to 17mm. -> This is definitely a tapered thread.
I think for tapered NPT threads in cast aluminum holes correct tightening procedures are very important, they can be easily over-tightened.
Perhaps ~ 20Nm (15 ft-lbs) was already too much in this case!
In future I´ll follow Gall757´s tightening advice for NPT-fittings : "The preferred way is to turn the part with your hand, and then turn 1.5 to 3 revolutions."
@fieromatty: Very nice that you donate your intake mani for my Fiero! But I´ll check out if the Fiero also starts with the "Camarobird" LIM before I transfer the money for shipping your Fiero-LIM to Austria.
Maybe the Fiero also starts without cold start injector (Camarobird LIM)? If not, I´ll transfer the money for shipping the Fiero-LIM to your PayPal-account.
Today I´ll check out whether the Camarobird lower intake fits the Fiero or not. I´ll post some comparison images between Fiero and Camarobird LIM.
If it makes you feel any better I did the same exact thing... I don't think I've ever been so pissed at myself or my Fiero then I was that day. A ten minute project turned out to be a weekend from hell, you'd think Rodney would send some warning about overtightning but I guess a real mechanic would know better. Anyway it was a learning experience, I'll never make that mistake again.
[This message has been edited by JCircs (edited 01-18-2015).]
Teflon tape: use 2-3 full wraps of tape depending fitting size. Tape should not be used on senders that ground thru the threads. Sometimes the tape gives a poor or no electric connection.
This is incorrect information.
Teflon tape is wrapped 1 1/4 to 1 1/2 turns maximum, just enough to cover the threads and not slip. The tape should be installed so that the tape tightens on the wrapped item as it is threaded in. Properly used, Teflon tape will cause no grounding issues on sensors when properly tightened.
Teflon tape is wrapped 1 1/4 to 1 1/2 turns maximum, just enough to cover the threads and not slip. The tape should be installed so that the tape tightens on the wrapped item as it is threaded in. Properly used, Teflon tape will cause no grounding issues on sensors when properly tightened.
I'm in Theorge corner on this one. The issue being "continuity" especially on a single wire sensor such as the O2 sensor on Fiero's. Yes the teflon will be cut away to a degree when the sensor is tighten into a tapered thread but it is still there with the potential to increase resistance. This can be verified with a meter. Another parallel would be mild oxidation on a battery terminal. A clean shiny terminal or an oxidized one will both start the car but the shiny one will conduct better due to improved grounding.
And of course I respect both gentlemen's opinions.
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
I'm in Theorge corner on this one. The issue being "continuity" especially on a single wire sensor such as the O2 sensor on Fiero's. Yes the teflon will be cut away to a degree when the sensor is tighten into a tapered thread but it is still there with the potential to increase resistance. This can be verified with a meter. Another parallel would be mild oxidation on a battery terminal. A clean shiny terminal or an oxidized one will both start the car but the shiny one will conduct better due to improved grounding.
And of course I respect both gentlemen's opinions.
Spoon
My statement is not based upon my opinion, but the Teflon tape manufacturers published information on proper utilization of their product. I have NEVER had continuity issues when using the PROPER amount of Teflon tape on tapered threads.
Here are some comparison images between Firebird 3.4PR and Fiero lower intake manifolds:
Fiero intermediate intake test-fitted on the Firebird LIM:
As you can see the intakes fit together without any problems!
Also all Fiero lower intake sensors (expect cold start injector sw) can be installed on the Firebird intake without any issues. In the Firebird coolant pipe fitting hole the Fiero ECT-sensor comes in and the Firebird ECT-sensor is replaced by the Fiero fan temp switch.
Only one thing I´m not sure about is, whether my Fiero will start without a cold start injector at temperatures near freezing point?
Here is a picture of the Fiero's cold start injector holes:
Originally posted by olejoedad: This is incorrect information.
Teflon tape is wrapped 1 1/4 to 1 1/2 turns maximum, just enough to cover the threads and not slip. The tape should be installed so that the tape tightens on the wrapped item as it is threaded in. Properly used, Teflon tape will cause no grounding issues on sensors when properly tightened.
Source? Because many sites don't agree, including tape makers... Oatey white tape pdf available tru too many places to list. Apply the thread seal tape a minimum of three wraps, using care to wrap in the direction of the thread rotation.
Swagelok tape page 3. ... wrap two to three revolutions of tape. ... Swagelok PTFE tape is thicker than the average hardware store PTFE tape, so two to three revolutions is enough. and swagelok video (youtube)
Many others calls for 3-6 turns... Sealing threads... I have good results 2-3 turns of tape on brass body sensors/senders bolted into aluminum parts. I had some poor grounding using tape.
My information came from the manufacturers about thirty years ago. I did a lot of industrial plumbing and pipefitting in the chemical process industry. The purpose of the tape is not to seal, as the tapered threads do that, but rather to allow disassembly when and if needed in the future. I have installed hundreds of sensors, industrial and automotive, using the one and a quarter to one and a half turn method and have never had issues with poor continuity, leakage or disassembly.
Perhaps the marketing department is now writing the directions, rather than the engineering department.
Fortunately it's pretty easy checking for continuity/bad ground by using a multimeter... checking from the manifold to the base of the fitting. I've used Teflon tape for at least a couple of decades and have never had a problem with the fitting not grounding properly.
Seems to me the only time there'd be a problem with using Teflon tape is if it was wound round and around and around and around and around...
Are there different thicknesses of Teflon tape? The tape I have (and I've used the same small roll all these years) is so thin you can practically see through it.
@Gall757 Which throttle body connection do you mean, the air supply pipe over the cold start injector which connects to the TB? I think this is just additional air for the cold start injector for obtaining an inflammable mixture while cold starting (otherwise AFR will be too rich while cranking)?
Originally posted by Patrick: Fortunately it's pretty easy checking for continuity/bad ground by using a multimeter... checking from the manifold to the base of the fitting. I've used Teflon tape for at least a couple of decades and have never had a problem with the fitting not grounding properly.
Seems to me the only time there'd be a problem with using Teflon tape is if it was wound round and around and around and around and around...
Are there different thicknesses of Teflon tape? The tape I have (and I've used the same small roll all these years) is so thin you can practically see through it.
I know how to test grounds... If you have problem then you have to take apart, make sure old tape is removed from both threads, and try again. Is a pain to do. I've had ground problems when owners or another shop got sloppy using tape. There are some rules using tape sealer.
Thickness... Yes and not only thickness, they have different colors but Many times Colors doesn't = thickness. Some "premium" white is often thicker, 4-6mils, while normal ones are 2-3mils, some "Cheap" maybe less. Thin tapes work but often need more too. Color often reflect tape density etc... http://en.wikipedia.org/wik...read_seal_tape#Types Some colors are just marketing... like Blue Monster™ tape. "Premium" "Cheap" doesn't mean much this time and why the quotes. Oatey White, Blue Monster, etc makes 2-3mil PTFE tape.
I don't know for sure, but that is my suspicion. You may need the vacuum to make the throttle body / IAC perform properly.
Olejoedad can probably help here...
Do you think this will work as alternative hose routing for a functional IAC system
Using EGR port:
illustrative image
The only difference is that the air has a longer way to the cylinders, but basically it should have the same functionality than the OEM cold start valve air tube.
[This message has been edited by Moar (edited 05-09-2015).]
I would eliminate the tube and plug the hole on the throttle body. The tube supplies air to the cold start injector passage.
OK, for the first test run with the Firebird lower intake I´ll plug the cold start valve air tube hole on the TB. If there are any problems with the IAC system at cold start (e.g. idle speed does not increase when engine is cold) I´ll remove the UIM again and will try out my "EGR-IAC" mod.
I think with the "EGR-IAC" mod (see image in my last post) the Fiero IAC will basically work like most IAC-systems on other engines.
yes, there are updates. In the meantime, I have made great progress.
I was quite occupied last several weeks, therefore I had no time to upload new pictures. I think I´m a little perfectionist, therefore I always need some more time to finish my work.
As the rocker covers were removed, I also took the opportunity to adjust the valve lash / preload. After this, I even polished the rocker covers to a mirror like finish. The valve cover polishing job was the most time consuming work on my Fiero so far!
Summary - Current Status:
- ported LIM - port matched TB, UIM -to- intermediate intake, intermediate intake -to- LIM - sandblasted intake manifolds - painted intermediate intake and LIM in silver-chrome - protected polished valve covers and fuel rail with Glisten PC (POR-15) clear coat - valve lash adjustment - rebuilt distributor + new paint for dizzy & ignition coil - new spark plugs - installed LIM + new low-temp fan switch + new low-temp thermostat - installed intermediate intake runners - installed 3.4 Firebird injectors + Fiero fuel rail - modified PCV system - EGR-delete (reused EGR tube for bypassing air from IAC valve btwn. TB & UIM)
Step by step assembly process:
1.) Porting and port-matching:
First I started to mark all matching surfaces with paint while using the gaskets as template for obtaining the correct contours:
Then I started with the port matching job which needed several hours with non-professional tools. I used a usual big drilling machine with low-quality milling cutters for coarse material removal and a small dremel tool for grinding a nice finish:
LIM:
Intermediate intake runner:
UIM:
TB:
Then I ported the LIM ports more or less completely trough inlet to outlet side:
BTW, in case of the Firebird/Camaro 3.4PR LIM, no welding is needed for grinding the injector humps to small ramps! If you want to grind the exaggerated humps form the Fiero LIM, I´d recommend to weld some material on the opposite wall side of the LIM.
Why? See these pictures for comparison btwn. Fiero and Firebird/Camaro LIM:
Fiero LIM with large diameter countersink for injectors (therefore large humps in the ports):
Firebird/Camaro LIM without machined surface (therefore only small humps in the ports):
Comparisons of humps before porting:
You can see, that there is a severe difference in size of these injector humps! Therefore the use of the Firebird/Camaro LIM should result in a better breathing engine.
As I used the Firebird/Camaro LIM I just needed to grind the hump slightly in order to get a nice small ramp. This small ramp will still increase intake air velocity and still creates some turbulence for ensuring sufficient intermixture of air and fuel.
2.) Painting Intake Manifolds:
I painted the lower intake mani and intermediate intake with high-quality silver-chrome paint:
I also painted some bolts with alkyd resin paint while using linseed oil as thinner: Linseed oil gives the paint better elastic properties and makes a glossy smooth surface!
3.) Polishing Valve Covers:
After several hundreds of hours I finally got this …
Looks like chrome, doesn´t it?
Then I brushed the covers with 2 thick layers Glisten PC clear for protecting the mirror polished surface against oxidation and scratches.
Finished valve covers with Glisten PC clear:
I know the chrome effect is a little bit diminished due to the thick layers of clear coat now.
Maybe, I will need to remove the rocker covers in 1 or 2 years and then I´ll take the opportunity and will polish the completely cured clear coat.
4.) Distributor Rebuild:
Before:
After:
5.) Assembly:
Bolted Firebird LIM to Fiero engine and installed low-temp fan switch BWD #TFS4:
Installed dizzy and freshly painted coolant neck with 180°F Sant thermostat:
Valve covers installed:
Firebird fuel injectors painted in yellow (= car color) and fuel rail coated with Glisten PC clear:
If you convert over to the 7730 ecm, you won't need the cold start injector anymore, plus the engine will run smoother too. Before the 7730 conversion, my csi was disconnected and it always started right up. On one morning that was 18°F, it took a second to fire, but no problems after started. I wouldn't worry about it.
[This message has been edited by f85gtron (edited 05-04-2015).]
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