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What could be causing premature Saturn engine failures due to overheating?
Q: What could be causing premature Saturn engine failures due to overheating?
A: Here’s information that can be helpful to your installer customers and can help prevent premature rebuilds due to overheating. The AERA Technical Committee offers the following information on an engine coolant leak on 2000-2001 GM 1.9L DOHC engines. These engines are used in the Saturn vehicles made by GM. Vehicles affected are up to and including VIN 1Z305500. Customers may notice a loss of engine coolant, low coolant levels and/or engine overheating.
Coolant loss may be due to an intake manifold gasket leak at the coolant passage located behind the number four cylinder intake port, possibly during cold engine operating conditions.
To prevent coolant loss, Saturn has revised the intake manifold gasket for those DOHC engines. The new gasket is a two-piece design as shown in Figure 1 consisting of a separate coolant seal (1) that is made of a different material and is black in color and a shortened intake manifold gasket (2) of the same material and orange in color as in the original one-piece design.
Q: Are the crankshafts used in 1991-2002 Ford 4.6L VIN 6, engines all the same?
A: No. According to the AERA Technical Committee. the 1991-2002 Ford 4.6L VIN 6, 9, W & X engines use two different design blocks depending on the application and at which engine plant they were manufactured, either Romeo or Windsor.
There are several significant differences to help distinguish blocks.
Note: All vertical main cap bolts require replacement each time they’ve been torqued. Do not reuse during engine assembly. However, dowels, jackscrews (left hand threads) and side bolts (cross bolts) MAY be reused.
These engines use two vertical bolts in each main cap, jack screws that preload the block/cap joint, cross bolts that attach main caps to the block skirt and flanged thrust bearing in #5 cap.
Caution: Ensure jackscrews are bottomed (screwed into the main caps) before installing the main caps into position on the block. Tap the main bearing caps into position on the cylinder block before tightening bolts to specifications. This is done to ensure proper torque readings.
1. When installing main bearing caps, before tightening to specification, force crankshaft toward the front of the engine to align thrust bearing. The single thrust washer faces the rear of the engine with the oil groove facing out. Install the thrust main cap and position it so the rear-bearing surface is contacting the crankshaft.
2. Install new vertical main cap bolts (Bolts 1-10, Figure 2,) and tighten in sequence using 2 steps to specifications. Step one: 28-31 ft.lbs. (40 Nm), Step two: rotate all bolts in sequence 85°-95°.
3. The jackscrews are a part of the main bearing cap assembly, and are screwed into the main caps, not the cylinder block. Back out the jackscrews (Bolts 11-20, Figure 3) against the cylinder block in two steps in the sequence shown. Step 1: Tighten to 44.6 in.lbs. 5 Nm Step 2: Tighten to 80-97 in.lbs. (9-11 Nm).
4. Tighten main cap side bolts (Bolts 21-30) in sequence as shown in Figure 4, left. Step 1: Tighten to 89.2 in.lbs. (10 Nm). Step 2: Tighten to 14-17 ft.lbs. (19-23 Nm).
These engines use two vertical bolts in each main cap, dowels at the block/cap joint and cross bolts that attach main caps to the block skirt. Two half thrust are used on the number five main bearing; no thrust on #5 cap. The dowel pins used should be positioned so their flat sides face the crankshaft. Follow the procedure below and reference Figures 2 and 4 for Windsor engines.
1. Install new vertical main cap bolts (Bolts 1-10) and tighten in sequence using 2 steps to specifications as shown in Figure 2. Step 1: 30 ft.lbs. (40 Nm); step 2: rotate all bolts in sequence an additional 85°-95°.
2. Install side bolts and tighten in sequence using 2 steps to specifications as shown in Figure 4. Step 1: 20-24 ft.lbs. (27-33 Nm); step 2: rotate all bolts in sequence an additional 85°-95°. EB
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