Tomte

Hi,



Upon recommendation from Stocker I opened a new thread as this might get things sorted quicker. All info from this thread up to 15 August 2011 is included in this initial post.



The problem:

I own a 2001 Tiburon RD2 with a G4GF-EG engine (a 99kW Beta I - adapted to European emission standards) with FIN (VIN) KMHJG31FP1U215448 and key numbers 8252(at 2.1) and 396 (at 2.2). My exhaust manifold cracked. The replacemente part (28510-23720 or 28510-23721 is a catalytic converter and exhaust manifold as one part) costs around 850 € - and that is already crossing a border to lower the price. I want to change the exhaust anyway, but it is a bit difficult to modify it and still be allowed to drive the car in Germany. If the parts appear to be aftermarket and do not have an E-number or ABE (official identification numbers stating the part may be used in the car) they may not be used in that car. There are no such parts available in Europe - except original parts. I do not really have the time to figure out a streetlegal header setup with changed catalytic converters which would pass thorough testing by the TÜV (the test itself can be >500€) as I do not have a spare car and my warrant of fitness (HU) expired.

EDIT 8-15-2011: I took pictures of the manifold and misplaced them There were actually 4 cracks ranging from 3 to 12 centimeters.



Possible US solutions that don't apply in my case

* Stocker mentioned that cracking of the header was covered in the US. I had also read that on several forums. This warranty only covers a vehicles lifespan which is 100,000 miles or ten years I think (source: Hyundai and EPA) - EDIT apparantly Stocker had his replaced at a higher milage (see below). My car would still fit in there (1 Dec 2001 and 131,000km) if I were in the US.

EDIT 8-15-2011: In Germany/Europe the warranty period of Hyundai is 60 months or a certain milage in my case (now it would be 84 months with Hyundai/Kia). All RDs would not be in the warranty period.



Possible Solutions:

* I looked into just getting it repaired (welded). As we all know it requires some expertise to weld cast iron if you want it to last. I found someone that would be able to do that for >140 € if I bring him the header(company info attached). They already did that on a similar header of a Lantra 102 kW (part number 28510-23450). According to the owner that thing is still alright after 6 months with little driving and no LPG. Combustion is a bit "dryer" with LPG and longer, hence more friction and heat dissipation to the header - thus more strain on the header. I drive a lot at the moment and at high speeds (Autobahn) Edit 8-15-2011 (180kph at 5000rpm). I would prefer a replacement part as I heard numerous times how unpredictable the outcome is.

EDIT 8-15-2011: I did have it welded. A friend of mine owns a metal working shop (can provide address if needed) and welded it for free He actually does that all the time (usually for OPEL ). I just forgot to ask him. Took pictures of the weld, but guess what: I misplaced them now, 5000km later, it is still holding up .

* I tiped in "2001 Hyundai Tiburon exhaust manifold" on google. There are quite a few listed for the G4CP engine (part number 28510-23431). Those Dorman/eastern catalytic headers look stock enough to probably fool the TÃœV and 28510-23XXX parts are compatible in many cases. But apparently the Sirius engine and the Beta I engine are very different, so the 28510-23431 part won't fit, right? Would the Broadband Lambda probe (oxygen sensor) of the header be on the wrong side and would its thread be the same as in Europe?

EDIT 8-15-2011: It will not fit according to Hyundai.

* Does anyone know a two piece replacement option for part number 28510-23720 (or newer 28510-23721) or something that would fit the G4GF engine block and my catalytic converter if a flange were put in? I really just need the header, but it has to look stock ie no stainless steel parts ... for now that is

EDIT 8-15-2011: Stocker: In the USA, earlier years (1998 at least) had a two-part system where the manifold was separate from the converter, but those also crack, because no slices are put in the flange.



EDIT 8-15-2011:

* Brazing seemed to be an option (see my post from 6-24-2011 below). I talked to my friend the metal worker. He does have the facilities to do it (precise oven), but said that it was pointless. It would be better to use high temperature brazing >800°C. That would damage the attached catalytic converter though. The lower temperature option would only be stable up to somewhere between 400 and 450°C. According to stocker the manifold doesn't get hot enough to harm the brazing, but apparantly that is up for discussion as I was told by several people that it will heat up above 400°C in my case (LPG and high speed driving with occasional lean fuel mixture). If I get my hands on an infrared thermometer I will measure the temperature of the manifold under several conditions

An issue with both brazing and welding is that the welds are less ductile than the cast iron manifold. That puts strain on the manifold which might crack in other locations. Only if the welds are bad they will desintigrate/loose bonding and leak.



EDIT 8-15-2011:

What if it is so rusty you cannot remove it:

Stocker: Removing the heat shield: penetrating oil, light tapping with a hammer on the bolt, more penetrating oil, tapping, over the course of several hours. THEN try to tighten a little bit with a socket wrench, THEN once it cracks loose try to remove bolts. This MUST be specifically a penetrating oil as lubricating oils will NOT get into the threads.

This did not work for me though Had my garage remove it due to lack of time. Aparrently there a other tricks as well:

First just hit the bolt with a hammer. Try loosening. Instead of penetrating oil you could try rust dissolver (their working mechanisms are mutually exclusive if the dissolver has not dried up!!!) You can also use graphite (which may be combined with penetrating oil). Heat with a small gas burner (those kitchen things suffice) - Oil might ignite! Use a mechanical impact wrench (10-20€) or pneumatic impact wrench if available.



Sorry for making this so long, but I wanted to be as clear as possible and provide info so others with a similar problem would not have to look around as much as I did. Help and opinions are greatly appreciated. Please feel free to comment on the structure of the post as well so I can make smoother posts in the future . Thank you.



Greetings from overseas

Stocker

It would surprise me if a sirius manifold would work for you



I don't know how they play in Europe but my manifold was replaced well into the 2nd 100,000 miles with no difficulty. That is because the converter is supposed to never fail and the manifold is considered part of the converter for emissions regulation purposes.



Welding: you might also look into brazing. I have seen it done on engine blocks but I don't know if it would take exhaust manifold heat. If you have a shop that can do the welding, that may actually turn into your best option.



Removing the heat shield: penetrating oil, light tapping with a hammer on the bolt, more penetrating oil, tapping, over the course of several hours. THEN try to tighten a little bit with a socket wrench, THEN once it cracks loose try to remove bolts. This MUST be specifically a penetrating oil as lubricating oils will NOT get into the threads.



In the USA, earlier years (1998 at least) had a two-part system where the manifold was separate from the converter. That manifold would also crack.



The cracking is caused by not putting slices in the flange. The replacement will crack again and welding is cheaper than replacement, especially if you have to do it TWICE and Hyundai won't pay for it.

Tomte

did some more digging and inquiring



Warranty:

Definite answer from Hyundai: The warranty period in Germany is 60 months (or a certain milage) in my case (now it would be 84 months with Hyundai/Kia). All RDs would not be in the warranty period. Bummer.



Brazing:

found this on hybrid Z - site for nissan/datsun Z models:

1st quote: "I have had good success in the past with brazing exhaust manifolds. The key is surface preparation and pre heating. first use a die grinder w/ a carbide cutter to cut at least an 1/8" deep groove in the full length of the crack.I heat the entire area surrounding the crack red hot with a torch.while it`s still hot I use an air hammer with a sharp pointed bit to chip the entire area,putting small punch marks all over the area to be brazed. As a manifold ages,a thin crust of rust forms over the surface.This chipping will remove the crust as well as creating a good "toothed" surface for the brass to adhere to.The heat helps to loosen the crust.Finally,Reheat as much of the area to red hot(and keep it red) as possible while brazing. One of the manifolds that I brazed this way has aquired over 25,000 mi so far with no problems at all. Yes it`s time consuming but If done correctly it will be a permanent repair and possibly stronger than new. Also... If at all possible try to clamp the manifold securely to minimize warping.I usually take them to a machine shop to have them resurfaced after brazing."

2nd quote:"I have also welded the exhaust manifold on the 4.3 in my Z. I had to cut the flange off and move it inboard about 3/4" and re-weld it (otherwise it hit the frame). That was over 1.5 years ago, and no problems. I just used a mig welder and gobbed lots of filler on there. I haven't pulled it off to inspect it, but it definitely doesn't leak.

What I would suggest, before you buy another manifold, is to try just welding up the one you have; you don't have much to lose by doing that except the pain of pulling it off again if it doesn't work.

What I would do is use a die grinder to V the crack about halfway through the thickness of the casting (make sure to V it well past the visible ends of the crack) and then try welding in spots until the entire crack is covered and filled; giving it time to cool in between adjacent spots. That way you won't get the weld area too hot, and the shrinkage of the weld won't be as severe, which is what causes the cracking.

This method of welding in spots in alternating places is used in body shops to weld on replacement sheet metal pieces. It prevents the sheet metal from shrinking due to heating/cooling."

Discussion on cracked cast iron manifolds on HybridZ



A good description on cast iron repairs - i know it is about farm equipment

cast iron repairs



An issue with brazing?

The temperature of a catalytic converter is ideally about 500-600°C and may be up to 900°C. The reaction constants (k) are usually highest around 600°C i.e. the otherwise NATURALLY occuring reactions of the exhaust gases are accelerated most (about 350000times) at that temperature. Brazing is done above 800°C. Given my previous statements above about lpg and info found here Info on catalytic Converters in Motor vehicles in German I fear it might not last.



@stocker: tomorrow will be tapping day



Depending on how the catalytic converter looks I will have it welded next week to buy me some time to assemble a descent exhaust (I really wish I could have dealt with the exhaust after the intake )

Stocker

Remember that the hot exhaust gases are relatively cool vs. the blazing hot converter. The manifold has "cool" air running through it at all times, and converters are only really hot during operation when there is lots of extra hydrocarbon in the exhaust (rich, e.g. high speed operation). I would not worry about at least trying to have the manifold brazed, but each man has his own comfort level.

Tomte

original post updated - hope it helps someone in the future. If anyone has some more info or other feedback please chime in

Stocker

It makes me happy to know that there are still small welders doing side jobs for friends free of charge. Good job.