I am currently having an issue with my lst setup and thought i would pick some other lst owners brains. My setup is an 81.5 lst with crower 403's in the head, felpro gasket, and arp headstuds torqued to 75. I am currently revving to 8700 @ the track with an ls water pump. My coolant temp seems to shoot up in pulls where i am in boost but does fine when I drive around. It blows out coolant out the overflow whenever i am in boost. Tried a new radiator cap and thats not it. Compression is pretty close accross the board (2%). Burped the system to get the bubbles out and still no workie. Any other lst guys experienced anything like this?

 

sounds like a head gasket

 

if you are blowing coolant every time you go boost it does sound like headlift/headgasket issue.

 

indeed a headlift or head warpage issue. fix it before u break the motor big time. Also swap to a gsr water pump and belt for those rpms.

 

i agree if its pushing coolant it has to a h/g or warped or something to that effect

 

some things that may solve your issue...

-new hg, slightly thicker than the .030mm one you probably have on there
-a 22t water pump which means you will need a GsR oil pump
- re- torquing your head studs down to 80 ft lbs wont hurt it
- getting all your air pockets out

 

^^^
LS and GSR oil pumps are the same part number

 

The car is parked for now anyways since I got the boot at the track. Just wanted some second hand advice as well. I think I am going to pull it and get the head o ringed with a copper gasket and have it checked for flatness. Some local guys have had luck with that or do you think it is excessive?

 

o-ringing the head is overkill, the drag cars don't even do that.

who tuned the car?

 

ls = 19 teeth
gsr = 22 teeth

the less teeth on the ls makes the impellar spin faster at any given rpm.
8700 is brave as hell with ls rockers.

if you take the head off to put a new hg on then you need to get the head milled down as it could likely be warped outside the service limit (which is retarded big anyway like .004)

retorquing to 80 ftlbs is good. i torque my b series arp studs to 80 in 3 steps ( 25/50/80), for the next time you have it all apart. just set the tq wrench to 80 and follow the sequence now with the head on.


ultimately, you could be running too much timing and have excessive cyl pressures. are there any signs of detonation on the plugs? whats your boost pressure and plug gap? whats the engine management and can you adjust it? if so, try pulling 2 degrees of timing and make another pass. if you dont loose mph and it doesnt blow coolant out than your tune was past max brake torque

 

he is right, the oil pumps all have the same number of teeth so if you change the water pump, you only have to have the matching belt.

 

Agreed.

Not exactly. Only 96+ are the same.

 

^^^

ahh, good to know..

 

Why do people ask questions and NOT LISTEN FOR THE ANSWERS???


Pushing coolant only during boost means a few things. When it only pushes out during boost, you have too high of cylinder pressures for the headbolts and/or HG. The biggest problem is your HG seal is allowing burning gasses from your cylinders into the coolant passages. That pushes coolant out the cap. That's typically caused from re-using stock headbolts (single-use only), not torquing them properly (RTFM!), and/or a shity HG (fel-pro). Rarely is it from a warped head or block - that will allow continuous leakage, burning your HG and really causing problems.

Fixes can be as simple as replacing the HG with an OEM MLS gasket, new head bolts (arp's are a better choice than OEM), and making sure your head/block are straight *AND* have the proper finish. The correct finish is VERY important: I got a GSR shortblock that someone must have used a angle grinder + sanding discs on. I got it cheap since...the head gasket blew! No surprise to me there.

 

Torqued properly via a honda oem service manual, arp head studs, motor has mas maybe 2500 miles on it so i was hoping it wasn't warped from the machine shop lmao. It is coming apart today to double check the flatness on the head and just going to get a oem head gasket and go from there.