08 nytro probem cant figure it out/can you?

[turbo_420a]

just bought an 08 nytro fx rtx (front cooler only) ran great on test drive and I loved it got it home and it overheated. It has an atermarket gauge on it and the stock light came on at 210 and I shut it down at 220. after some investigating realized the fan relay wasn't working. I replaced it and its still overheating. I then noticed the radiator was low on coolant and the reservoir was full so i filled it and ran the sled with a funnel cap tool installed to fully purp the system and the temp fluctuates normaly between 190-200 when the fan kicks on sitting in my garage. so I put a new radiator cap on it and rode it and same thing, rides fine for a wile and then gets hot (215) and I let it cool and the radiator is low and the reservoir is overfilling. So I did a pressure test on it and it held 15 lbs pressure for 15 min only dropping 1lb in that time. So I cant think its a head gasket because it holds pressure? where is this air pressure comming from thats forcing coolant out the motor overflowing the reservoir? im trying thermostate next?

 

[grizztracks]

You may have a head gasket issue. A bad gasket or warped head will allow engine compression to escape into the cooling jacket which will push coolant out the overflow and cause overheating. This is a common problem when the engine has been overheated. I've replaced a couple Nytro head gaskets with the same issue. If you look closely with the engine hot and running you can see very small air bubbles in the radiator. I have yet to see a bad coolant pump or thermostat on theses engines and they tend to purge air out after a few heat cycles so what you are describing points toward a head gasket replacement. Replacement requires pulling the engine to remove the head. The head will need to be checked for warpage and normally shaved at a machine shop ($40-60). Labor is the most expensive part of the job.

 

[turbo_420a]

Thats kinda what I thought to but why is the system holding pressure then when I put a gauge on it and pressurize it ?

 

[grizztracks]

Thats kinda what I thought to but why is the system holding pressure then when I put a gauge on it and pressurize it ?

You can't pressurize the cooling system anywhere near what the engine compression runs at. When the engine is hot things expand and with the engine compression running well over 100 psi a small amount of head warpage will result in what you are describing.

I'm fairly sure you have a head gasket issue and like I said it's not uncommon. If you can't see the bubbles in the radiator Here is a way to check for compression gases:

http://www.youtube.com/watch?v=DQwvdzRGKkI

http://www.napaonline.com/Catalog/Catal ... 0006398563

block chek: http://www.blockchek.com/store.htm

 

[turbo_420a]

wow thanks big help!!! I know there is a lot of variables involved but do you have a rought ball park on what a head gasket job cost? considering the head is in good shap. do the head bolts need to be replaced? how hot would it need to get before damage will occur? whats the normal opperating temp?

 

[grizztracks]

I'm not sure what temperature it takes to cause damage but if it overheated due to the lack of antifreeze or the fan not working then there is a good chance of damage. I believe the thermostat opens somewhere between 150 and 165 but I'm not sure at what temperature the fan kicks on or the overtemp light comes on. I know it's been documented here on TY in the past. It's common practice to replace the head bolts although most manufactures have a maximum length specification even though they are yield-to-torque bolts. If the bolts are within manufacture's specs some mechanics believe it's OK to reuse them one time. The last head gasket replacement job I did required some machining of the head ($60) and I charged $250 for labor. If I remember right the job took around 7-8 hrs.

 

[gmfamily2008]

my fan turns on at 195. I have a gauge in the line that sits just behind the fan .
worst part of the head job is that the cams need to come off and kept in time, also need to tilt the motor .... not just the simple drain the coolant and pull the head like a 2 smoke. best left to a dealer or mechanic who has had one apart b4. IMO . Good Luck

 

[grizztracks]

my fan turns on at 195. I have a gauge in the line that sits just behind the fan .
worst part of the head job is that the cams need to come off and kept in time, also need to tilt the motor .... not just the simple drain the coolant and pull the head like a 2 smoke. best left to a dealer or mechanic who has had one apart b4. IMO . Good Luck

Cams need to come out to remove head bolts so the timing will have to be reset when putting it back together. It's not that hard to reset the cams and chain. The motor actually needs to come out of the chassis to remove the head in a FX Nytro.

 

[dirk]

If your careful to not let the cam chain come off the crank and mark your cams/chain you don't have to worry about resetting the timing.

 

[grizztracks]

If your careful to not let the cam chain come off the crank and mark your cams/chain you don't have to worry about resetting the timing.

The cams have to be removed so regardless of what happens with the chain on the crank the timing will have to be reset.......... Always use the proper markings and procedure to reset the cams and crank timing. These are interference engines and you don't want to take any chances.

Procedure is similar to this: http://www.ty4stroke.com/viewtopic.php?t=90826

 

[pay2play]

Awesome tech thread! I know so much more than I did 2 minutes ago, thanks Grizz!

 

[mcamzr]

Awesome tech thread! I know so much more than I did 2 minutes ago, thanks Grizz!

X2. Not only did I learn something but now I'm stressed about mine lol. I overheated a lot last year and found the dealer put the wrong coolant in the sled and it ate through the rad. I replaced that and added a tunnel cooler but haven't had trail time to test it. I hope the head is ok.

 

[dirk]

If your careful to not let the cam chain come off the crank and mark your cams/chain you don't have to worry about resetting the timing.

The cams have to be removed so regardless of what happens with the chain on the crank the timing will have to be reset.......... Always use the proper markings and procedure to reset the cams and crank timing. These are interference engines and you don't want to take any chances.

Procedure is similar to this: http://www.ty4stroke.com/viewtopic.php?t=90826

If you put a paint mark on the cam sprocket and chain and don't let the chain move on the crank it is possible to remove the head without resetting the timing. It's obviously much better to set it properly but in a pinch or when setting valve clearances this will work you just have to be very careful.

 

[09nytro]

If your careful to not let the cam chain come off the crank and mark your cams/chain you don't have to worry about resetting the timing.

The cams have to be removed so regardless of what happens with the chain on the crank the timing will have to be reset.......... Always use the proper markings and procedure to reset the cams and crank timing. These are interference engines and you don't want to take any chances.

Procedure is similar to this: http://www.ty4stroke.com/viewtopic.php?t=90826

If you put a paint mark on the cam sprocket and chain and don't let the chain move on the crank it is possible to remove the head without resetting the timing. It's obviously much better to set it properly but in a pinch or when setting valve clearances this will work you just have to be very careful.

I'm not saying it won't work but I wouldn't trust that , it's not hard to retime everything , if you are can take it part then you should be able to put it back together right by reading the manual , you should never be in a hurry when doing head work or any engine work

 

[turbo_420a]

ok had a long night in the garage last night (should have been a long night on the trai) and i still havent nailed this down consecutively enought to pull the motor and say with out a dought its a head gasket... last night I realized the light that was coming on was not the temp light I thought it was but the temp light is red and the light that has been coming on it actually the orange "!" engine code light. DId a diagnostic procedure and pulled one code 30 ="engine shut down due to oil pressure drop" but the engine has never shot off on its own and this indcator light only comes on and goes back off everytime the sled gets up to 210-215 NOT the red temp light. The red temp has never came. And besides the diagnostics light coming on I replaced the radiator cap and replaced the thermostat with a sst washer to simulate an open thermostat and ran the engine with with the radiator cap removed and re purped the system and it ran for 20min in my garage with hardly no bubbles coming up in the radiator and temp fluctuated normaly from 185-200 and back down again. soI took it for a ride and once agian temp went up to 215 and the reservoir was full and the radiator was damn near empty and the diagnostic light not the temp light came on?????

oil level has always stayed right on the "H" on the dip stick and doesnt look milky, its relatively thin and brown looking.