Do I need to rebuild twins?
03-23-15, 11:29 PM
#1
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Do I need to rebuild twins?
To be clear, I am running a 13b-re cosmo engine with the twins: hitachi ht10's and not the normal hitachi fd ht12's.
I have put less than 2000 miles on them since I purchased the jspec engine. Rich afr's, 50/50 water meth injection at throttle body not pre turbo (unsure if pre turbo was safe to do on these guys) and running between 10 and 14 psi for those 2000 miles.
I pulled apart my manifolds to be repainted or possibly powder coated and noticed that the Y pipe (pressure charge pipe) has a little oil residue covering the inside on the front turbo. The rear turbo has no oil residue at all, and little to no shaft play. The front turbo does have some shaft play side to side and a little shaft play in and out slightly. The little vacuum/pressure nipple ports on the front turbo also had a little oil built up in there when I pulled the vacuum caps off. By the looks of it, These vacuum ports are directly routed from the front turbo pressure side in the compressor housing. This leads me to believe that my front turbo on the cosmo twins may have blown a seal!
My question is, should I be alarmed that there is a little oil? Are the twins on their way out? I read that some people say its okay to have a little oil on the wheel area but no one talked about a little oil on the pressure side.
If they need a rebuild I noticed a few kits on ebay supposedly claiming to fit the ht10's and also the ht12's? I cannot afford bnr, so please do not offer. Just need to be safe and rebuild myself If I can find the seals to suit my cosmo twins.
Sorry for the long post but wanted to be thorough! I searched but little info on my situation.
I have put less than 2000 miles on them since I purchased the jspec engine. Rich afr's, 50/50 water meth injection at throttle body not pre turbo (unsure if pre turbo was safe to do on these guys) and running between 10 and 14 psi for those 2000 miles.
I pulled apart my manifolds to be repainted or possibly powder coated and noticed that the Y pipe (pressure charge pipe) has a little oil residue covering the inside on the front turbo. The rear turbo has no oil residue at all, and little to no shaft play. The front turbo does have some shaft play side to side and a little shaft play in and out slightly. The little vacuum/pressure nipple ports on the front turbo also had a little oil built up in there when I pulled the vacuum caps off. By the looks of it, These vacuum ports are directly routed from the front turbo pressure side in the compressor housing. This leads me to believe that my front turbo on the cosmo twins may have blown a seal!
My question is, should I be alarmed that there is a little oil? Are the twins on their way out? I read that some people say its okay to have a little oil on the wheel area but no one talked about a little oil on the pressure side.
If they need a rebuild I noticed a few kits on ebay supposedly claiming to fit the ht10's and also the ht12's? I cannot afford bnr, so please do not offer. Just need to be safe and rebuild myself If I can find the seals to suit my cosmo twins.
Sorry for the long post but wanted to be thorough! I searched but little info on my situation.
03-24-15, 09:32 AM
#2
Depending on how you have the vacuum lines hooked up, in the stock configuration the PCV vapors are routed to the inlet of the front/primary turbo. So some oil here would be normal.
However, in and out shaft play is very bad. That is usually indicative of needing to be rebuilt.
Turbo rebuilds are not a DIY thing as they SHOULD be balanced when reassembled. Anything that spins 100-200,000RPM is balance criticlal. Ideally, if you source the parts, a local diesel (big truck) repair shop normally has the facility/equipment to do this.
On another note though: 14PSI is typically the max you could run the HT12s, that is probably TOO much for the smaller HT10s.
Vince
However, in and out shaft play is very bad. That is usually indicative of needing to be rebuilt.
Turbo rebuilds are not a DIY thing as they SHOULD be balanced when reassembled. Anything that spins 100-200,000RPM is balance criticlal. Ideally, if you source the parts, a local diesel (big truck) repair shop normally has the facility/equipment to do this.
On another note though: 14PSI is typically the max you could run the HT12s, that is probably TOO much for the smaller HT10s.
Vince
03-24-15, 10:28 PM
#3
Its been well documented that rebuilding the twins doesn't work out too well. What happens is the housings get distorted from all the heat, and the new parts don't fit right, and fail prematurely. A little oil is normal as the stupid stock pcv system dumps into the turbo inlet. Running a catch and better crankcase ventilation helps. A little shaft play is normal. If they boost fine and smoke, I'd leave them alone. The only solution for twins I recommend is from BNR.
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